Storage medium, reproducing method, and recording method

ABSTRACT

According to one embodiment, a storage medium comprises a transparent resin substrate on which a groove is formed, a recording layer formed on the groove on the transparent resin substrate, the recording layer using an organic dye material and recording information with a light beam of 620 nm or less in wavelength, a reflection layer formed on the recording layer, and a prevention layer formed between the recording layer and the reflection layer, the prevention layer preventing degradation of characteristics of the reflection layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2005-104725, filed Mar. 31, 2005, theentire contents of which are incorporated herein by reference.

BACKGROUND

1. Field

One embodiment of the invention relates to a storage medium such as anoptical disk, a reproducing method, and a recording method of thestorage medium capable of recording and reproducing information with alaser light beam having a short wavelength such as a blue laser lightbeam.

2. Description of the Related Art

As is well known, in recent years, with prevalence of personal computersor the like, media for accumulating digital data has been increasinglyimportant. For example, currently, an information storage medium capableof digitally recording and reproducing video image information and voiceinformation or the like for a long time is prevalent. In addition, aninformation storage medium for digital recording and reproduction isused for a mobile device such as a cellular phone.

As an information storage medium of this type, there is often utilized amedium of disk shape because the medium has a large capacity ofrecording information; has random access performance capable of speedilymaking a search for desired recording information; and moreover, themedium is small in size and light in weight, excellent in storageproperty and portability, and is inexpensive.

In addition, as an information storage medium of such a disk shape,currently, there is mainly used a so called optical disk capable ofrecording and reproducing information in a non-contact manner byirradiating a laser light beam. This optical disk primarily conforms toa CD (Compact Disk) standard or a DVD (Digital Versatile Disk) standard,and is compatible with both of these standards.

There are three types of optical disks, i.e., a read-only type whichcannot record information such as a CD-DA (Digital Audio), a CD-ROM(Read-Only Memory), a DVD-V (Video), or a DVD-ROM and the like; awrite-once type capable of recording information only once such as aCD-R (Recordable) or a DVD-R and the like; and a rewritable type capableof rewriting information any times such as a CD-RW (Rewritable) or aDVD-RW and the like.

Among them, as a recordable disk, a write-once type optical disk usingan organic dye for a recording layer is the most prevalent because ofits low manufacturing cost. This is because, if an information recordingcapacity exceeds 700 MB (Mega Bytes), there is almost no need forerasing recorded information and rewriting new information, andeventually only one recording suffices.

In the write-once type optical disk using the organic dye for therecording layer, after a recording area (track) specified by a groove isirradiated with a laser light beam and a resin substrate is excessivelyheated to its glass transition point Tg or more, an organic dye film inthe groove causes an opto-chemical reaction and produces a negativepressure. As a result, the resin substrate is deformed in the groove. Arecording mark is formed by utilizing this deformation.

A typical organic dye used for a CD-R whose wavelength of a recordingand reproducing laser light beam is about 780 nm includes aphthalocyanine based dye such as IRGAPHOR Ultragreen MX available fromCiba Speciality Chemicals. In addition, a typical organic dye used for aDVD-R whose wavelength of a recording and reproducing laser light beamis about 650 nm includes an azo metal complex based dye available fromMitsubishi Kagaku Media Co., Ltd.

In the meantime, in comparison with a current optical disk, in a nextgeneration optical disk which achieves recording and reproduction withhigher density and higher performance, a blue laser light beam whosewavelength is short at about 405 nm is used as a recording andreproducing laser light beam. However, an organic dye material capableof obtaining practically sufficient recording and reproducingcharacteristics by using a light beam having such a short wavelength hasnot been developed yet.

In document 1 (Jpn. Pat. Appln. KOKAI Publication No. 2002-74740), thereis disclosed an optical storage medium having a longer wavelength than awavelength of a write light beam in absorption extremity of an organicdye compound contained in a recording layer. However, in this document1, for example, there is nowhere described a configuration of enhancingperformance of an optical disk itself such as durability in the casewhere a mark recorded in an optical disk has been continuouslyreproduced by a blue laser light pickup. There is a need for a signalnot to be degraded in the case where a certain track is continuouslyreproduced. A write-once type optical disk using an excellent dye inreproduction light stability must be provided.

In document 2 (Jpn. Pat. Appln. KOKAI Publication No. 2004-139712),there is disclosed an Ag-group alloy reflection film or a semipermeablereflection film for an optical information recording medium, theAg-group alloy reflection film being made of an Ag-group alloycontaining 0.005 at % to 0.40 at % of Bi and/or Sb in total. However,document 2 merely discloses a reflection film simplex, and does notdescribe how an organic dye component is used as a recording layer andhow the above-described storage medium is configured as using arecording and reproducing light beam having a short wavelength.

As has been described above, a conventional storage medium using anorganic dye material is not sufficient in reproduction durability count.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

A general architecture that implements the various feature of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is an exemplary view of the contents of constituent elements ofan information storage medium and a combination method in the presentembodiment;

FIGS. 2A, 2B, and 2C show exemplary views of difference in principle ofobtaining reproduction signal between phase change type recording filmand organic dye based recording film in which FIG. 2A shows a phasechange type recording film and FIG. 2B shows an organic dye basedrecording film;

FIG. 3 is an exemplary view showing a specific structural formula of thespecific content “(A3) azo-metal complex+Cu” of the information storagemedium constituent elements shown in FIG. 1;

FIG. 4 is an exemplary view showing an example of light absorptionspectrum characteristics of an organic dye recording material used for acurrent DVD-R disk;

FIGS. 5A and 5B show exemplary views of difference of light reflectionlayer shape in pre-pit/pre-groove areas between phase change typerecording film and organic dye based recording film in which FIG. 5Ashows a phase change recording film and FIG. 5B shows an organic dyerecording film;

FIGS. 6A and 6B are exemplary views each showing a plastic deformationsituation of a specific transparent substrate 2-2 at a position of arecording mark 9 in a write-once type information storage medium using aconventional organic dye material;

FIGS. 7A, 7B and 7C are exemplary views which relate to a shape ordimensions relating to a recording film, which easily causes a principleof recording;

FIGS. 8A, 8B and 8C are exemplary views showing characteristics of theshape and dimensions of the recording film;

FIG. 9 is an exemplary view of light absorption spectrum characteristicsin an unrecorded state in a “High to Low” (hereinafter, abbreviated toas an “H-L”) recording film;

FIG. 10 is an exemplary view of light absorption spectrumcharacteristics in a recording mark in the “H-L” recording film;

FIG. 11 is an exemplary view of a structure in an embodiment of aninformation recording/reproducing apparatus according to the invention;

FIG. 12 is an exemplary view showing a detailed structure of peripheralsections including a sync code position sampling unit 145 shown in FIG.11;

FIG. 13 is an exemplary view showing a signal processor circuit using aslice level detecting system;

FIG. 14 is an exemplary view showing a detailed structure in a slicer310 of FIG. 13;

FIG. 15 is an exemplary view showing a signal processor circuit using aPRML detecting technique;

FIG. 16 is an exemplary view showing a structure in a Viterbi decoder156 shown in FIG. 11 or FIG. 15;

FIG. 17 is an exemplary view showing a state transition in a PR(1, 2, 2,2, 1) class;

FIG. 18 is an exemplary view showing a wavelength (write strategy) of arecording pulse which carries out trial writing for a drive test zone;

FIG. 19 is an exemplary view showing a definition of a recording pulseshape;

FIGS. 20A, 20B and 20C are exemplary views of a recording pulse timingparameter setting table;

FIGS. 21A, 21B and 21C are exemplary views relating to values of eachparameter used when optimal recording power is checked;

FIG. 22 is an exemplary view showing a light reflection factor range ofnon-recording unit in an “H-L” recording film and a “Low to High”(hereinafter, abbreviated to as an “L-H”) recording film;

FIG. 23 is an exemplary view of a polarity of a detection signaldetected from the “H-L” recording film and the “L-H” recording film;

FIG. 24 is an exemplary view showing a comparison in light reflectionfactor between the “H-L” recording film and the “L-H” recording film;

FIG. 25 is an exemplary view of light absorption spectrumcharacteristics in an unrecorded state in the “L-H” recording film;

FIG. 26 is an exemplary view showing a light absorption spectrumcharacteristic change in a recorded state and an unrecorded state in the“L-H” recording film;

FIG. 27 is an exemplary general structural formula of a cyanine dyeutilized for a cation portion of the “L-H” recording film;

FIG. 28 is an exemplary general structural formula of a styril dyeutilized for a cation portion of the “L-H” recording film;

FIG. 29 is an exemplary general structural formula of a monomethinecyanine dye utilized for a cation portion of the “L-H” recording film;

FIG. 30 an exemplary general structural formula of a formazane metalcomplex utilized for an anion portion of the “L-H” recording film;

FIG. 31 is an exemplary view showing an example of a structure anddimensions in an information storage medium;

FIG. 32 is an exemplary view showing a value of a general parameter in aread-only type information storage medium;

FIG. 33 is an exemplary view showing a value of a general parameter in awrite-once type information storage medium;

FIG. 34 is an exemplary view showing a value of a general parameter in arewritable type information storage medium;

FIGS. 35A, 35B and 35C are exemplary views comparing a detailed datastructure in a system lead-in area SYLDI and a data lead-in area DTLDIin a variety of information storage mediums;

FIG. 36 is an exemplary view showing a data structure in an RMDdeprecation zone RDZ and a recording position management zone RMZ, whichexist in the write-once type information storage medium;

FIGS. 37A, 37B, 37C, 37D, 37E and 37F are exemplary views each showing acomparison of a data structure in a data area DTA and a data lead-outarea DTLDO in a variety of information storage mediums;

FIG. 38 is an exemplary view showing a data structure in recordingposition management data RMD;

FIG. 39 is an exemplary view showing a structure of a border area in awrite-once type information storage medium different from that in FIG.38;

FIG. 40 is an exemplary view showing a structure of a border area in awrite-once type information storage medium;

FIG. 41 is an exemplary view showing a data structure in a control datazone CDZ and an R physical information zone RIZ;

FIG. 42 is an exemplary view showing specific information contents inphysical format information PFI and R physical information formatinformation R_PFI;

FIG. 43 is an exemplary view showing a comparison of the contents ofdetailed information recorded in allocation place information on a dataarea DTA;

FIG. 44 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 45 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 46 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 47 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 48 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 49 is an exemplary view showing a detailed data structure inrecording position management data RMD;

FIG. 50 is an exemplary view showing a data structure in a data ID;

FIG. 51 is an exemplary view adopted to explain another embodimentrelevant to a data structure in recording position management data RMD;

FIG. 52 is an exemplary view adopted to explain the other embodimentrelevant to a data structure in recording position management data RMD;

FIG. 53 is an exemplary view showing another data structure in an RMDfield 1;

FIG. 54 is an exemplary view of another embodiment relating to physicalformat information and R physical format information.

FIG. 55 is an exemplary view showing another embodiment relating to adata structure in a control data zone;

FIG. 56 is an exemplary view schematically showing converting proceduresfor configuring a physical sector structure;

FIG. 57 is an exemplary view showing a structure in a data frame;

FIGS. 58A and 58B are exemplary views each showing an initial valueassigned to a shift register when creating a frame after scrambled and acircuit configuration of a feedback resistor;

FIG. 59 is an exemplary view of an ECC block structure;

FIG. 60 is an exemplary view of a frame arrangement after scrambled;

FIG. 61 is an exemplary view of a PO interleaving method;

FIGS. 62A and 62B are exemplary views each showing a structure in aphysical sector;

FIG. 63 is an exemplary view of the contents of a sync code pattern;

FIG. 64 is an exemplary view showing a detailed structure of an ECCblock after PO interleaved, shown in FIG. 61;

FIG. 65 is an exemplary view showing an example of a light absorptionspectrum characteristic change before and after recorded, in an “H-L”recording film;

FIG. 66 is an exemplary view showing an example of a light absorptionspectrum characteristic change before and after recorded, in an “L-H”recording film;

FIGS. 67A and 67B are exemplary views each showing a molecular structurechanging situation in an azo metal complex;

FIG. 68 is an exemplary view showing another example of a lightabsorption spectrum change before and after recorded, in an “L-H”recording film;

FIG. 69 is an exemplary view showing another example of a lightabsorption spectrum change before and after recorded, in an “H-L”recording film;

FIG. 70 is an exemplary view showing still another example of a lightabsorption spectrum change before and after recorded, in an “H-L”recording film;

FIGS. 71A and 71B are exemplary illustrative cross section of a pre-pitin a system lead-in area SYLDI;

FIG. 72 is an exemplary view of a reference code pattern;

FIG. 73 is an exemplary view showing a comparison in data recordingformat of each of a variety of information storage mediums;

FIGS. 74A and 74B are exemplary views of a comparison with aconventional example of a data structure in a variety of informationstorage mediums;

FIG. 75 is an exemplary view of a comparison with a conventional exampleof a data structure in a variety of information storage mediums;

FIG. 76 is an exemplary view of 180-degree phase modulation and an NRZtechnique in wobble modulation;

FIG. 77 is an exemplary view of a relationship between a wobble shapeand an address bit in an address bit area;

FIGS. 78A, 78B, 78C and 78D are comparative exemplary views of apositional relationship in a wobble sink pattern and a wobble data unit;

FIG. 79 is an exemplary view relating to a data structure in wobbleaddress information contained in a write-once type information storagemedium;

FIG. 80 is an exemplary view of an allocation place in a modulation areaon a write-once type information storage medium;

FIG. 81 is an exemplary view showing an allocation place in a physicalsegment on a write-once type information storage medium;

FIGS. 82A and 82B are exemplary views of a layout in a recordingcluster;

FIG. 83 is an exemplary view showing a data recording method forrewritable data recorded on a rewritable-type information storagemedium;

FIG. 84 is an exemplary view of a data random shift of the rewritabledata recorded on a rewritable-type information storage medium;

FIG. 85 is an exemplary view of a method for additionally describingwrite-once type data recorded on a write-once type information storagemedium;

FIG. 86 is an exemplary view of specification of an optical disk in Bformat;

FIG. 87 is a view showing an exemplary configuration of picket codes(error correcting blocks in the B format;

FIG. 88 is an exemplary view of a wobble address in B format;

FIG. 89 is an exemplary view showing a detailed structure of a wobbleaddress obtained by combining an MSK system and an STW system with eachother;

FIG. 90 is an exemplary view showing a unit of 56 wobbles and an ADIPunit expressing a bit of “0” or “1”;

FIG. 91 is an exemplary view showing an ADIP word consisting of 83 ADIPunits and showing an address;

FIG. 92 is an exemplary view showing an ADIP word;

FIG. 93 is an exemplary view showing 15 nibbles contained in an ADIPword;

FIG. 94 is an exemplary view showing a track structure in B format;

FIG. 95 is an exemplary view showing a recording frame in B format;

FIGS. 96A and 96B are exemplary views each showing a structure of arecording unit block;

FIG. 97 is an exemplary view showing data run in and data run outstructures;

FIG. 98 is an exemplary view showing allocation of data relating to awobble address;

FIGS. 99A and 99B are exemplary views each showing an area of guard 3arranged at the end of a data run out area;

FIGS. 100A, 100B, 100C, 100D, 100E, and 100F are exemplary views showinga method for producing a write-once type information storage medium;

FIGS. 101A, 101B, and 101C are exemplary views showing a method forproducing a stamper for producing a write-once type information storagemedium;

FIGS. 102A, 102B, 102C, 102D, and 102E are exemplary views showing amethod for producing a stamper for producing a write-once typeinformation storage medium;

FIG. 103 is an exemplary view showing a spin coat condition forproducing a write-once type information storage medium;

FIG. 104 is an exemplary a view illustrating a relationship between agroove and a land in a write-once type information storage medium;

FIG. 105 is an exemplary a waveform chart showing an example of a signalrecorded to carry out a test of recording and reproducing evaluation ina write-once type information storage medium;

FIG. 106 is an exemplary view showing a general structural formula oforganic metal complex simplex “A”;

FIG. 107 is an exemplary view showing a general structural formula oforganic metal complex simplex B;

FIG. 108 is an exemplary view showing a general structural formula oforganic dye metal complex cation and anion U;

FIG. 109 is an exemplary view showing a general structural formula oforganic dye metal complex cation and anion W;

FIG. 110 is an exemplary view showing a general structural formula ofazo phthalocyanine metal complex Y;

FIG. 111 is an exemplary view showing an example U1 of organic dye metalcomplex cation and anion U;

FIG. 112 is an exemplary view showing an example W1 of organic metalcomplex cation and anion W;

FIG. 113 is an exemplary view showing a formazane metal complex V;

FIG. 114 is an exemplary view showing an example of organic metalcomplex cation and anion W;

FIG. 115 is an exemplary view showing a general structural formula oforganic metal complex cation and anion WW;

FIG. 116 is an exemplary view showing a general structural formula oforganic metal complex cation and anion WWW;

FIG. 117 is an exemplary view showing a general structural formula oforganic metal complex cation and anion WWWW;

FIG. 118 is an exemplary view showing an example of organic metalcomplex cation and anion WW1;

FIG. 119 is an exemplary view showing an example of organic metalcomplex cation and anion WWW1;

FIG. 120 is an exemplary view showing an example of organic metalcomplex cation and anion WWWW1;

FIG. 121 is an exemplary view showing an example of organic metalcomplex cation and anion WWWW2;

FIG. 122 is an exemplary view showing a relationship (measurementresult) between reproduction laser power and reproduction durabilitycount for each organic dye material;

FIG. 123 is an exemplary view showing examples of binary types;

FIG. 124 is an exemplary view showing examples of tertiary types;

FIG. 125 is an exemplary view showing comparative examples;

FIG. 126 is an exemplary view showing combinations of reflection filmmaterials and constitution and organic dye materials for recording filmsof example 1;

FIG. 127 is an exemplary view showing evaluation results of example 1;

FIG. 128 is an exemplary view showing combinations of reflection filmmaterials and constitution and organic dye materials for recording filmsof example 1; and

FIG. 129 is an exemplary view showing evaluation results of example 2.

DETAILED DESCRIPTION

Various embodiments according to the invention will be describedhereinafter with reference to the accompanying drawings. In general,according to one embodiment of the invention, a storage medium comprisesa recording layer using an organic dye material formed on a substrate;and a reflection layer comprises Ag and an additive element whichprevents degradation of recording and reproducing characteristics due toreaction with Ag and the organic dye material.

Hereinafter, embodiments of a recording medium and a method forrecording and reproducing the recording medium according to theinvention will be described with reference to the accompanying drawings.

Summary of Characteristics and Advantageous Effect of the Invention

1) Relationship between track pitch/bit pitch and optimal recordingpower:

Conventionally, in the case of a principle of recording with a substrateshape change, if a track pitch is narrowed, a “cross-write” or a“cross-erase” occurs, and if bit pitches are narrowed, an inter-codecrosstalk occurs. As in the present embodiment, since a principle ofrecording without a substrate shape change is devised, it becomespossible to achieve high density by narrowing track pitches/bit pitches.In addition, at the same time, in the above described principle ofrecording, recording sensitivity is improved, enabling high speedrecording and multi-layering of a recording film because optimalrecording power can be lowly set.

2) In optical recording with a wavelength of 620 nm or less, an ECCblock is composed of a combination of a plurality of small ECC blocksand each item of data ID information in two sectors is disposed in asmall ECC block which is different from another:

According to the embodiment, as shown in FIG. 2B, a local opticalcharacteristic change in a recording layer 3-2 is a principle ofrecording, and thus, an arrival temperature in the recording layer 3-2at the time of recording is lower than that in the conventionalprinciple of recording due to plastic deformation of a transparentsubstrate or layer 2-2 or due to thermal decomposition or gasification(evaporation) of an organic dye recording material. Therefore, adifference between an arrival temperature and a recording temperature ina recording layer 3-2 at the time of playback is small. In the presentembodiment, an interleaving process between small ECC blocks and data IDallocation are contrived in one ECC block, thereby improvingreproduction reliability in the case where a recording film is degradedat the time of repetitive playback.

3) Recording is carried out by light having a wavelength which isshorter than 620 nm, and a recorded portion has a higher reflectionfactor than a non-recording portion:

Under the influence of absorption spectrum characteristics of a generalorganic dye material, under the control of light having a wavelengthwhich is shorter than 620 nm, the light absorbance is significantlylowered, and recording density is lowered. Therefore, a very largeamount of exposure is required to generate a substrate deformation whichis a principle of recording in a conventional DVD-R. By employing an“Low to High (hereinafter, abbreviated to as L-H) organic dye recordingmaterial” whose reflection factor is increased more significantly thanthat of an unrecorded portion in a portion (recording mark) recorded asin the present embodiment, a substrate deformation is eliminated byforming a recording mark using a “discoloring action due to dissociationof electron coupling”, and recording sensitivity is improved.

4) “L-H” organic dye recording film and PSK/FSK modulation wobblegroove:

Wobble synchronization at the time of playback can be easily obtained,and reproduction reliability of a wobble address is improved.

5) “L-H” organic dye recording film and reproduction signal modulationdegree rule:

A high C/N ratio relating to a reproduction signal from a recording markcan be ensured, and reproduction reliability from the recording mark isimproved.

6) Light reflection factor range in “L-H” organic dye recording film andmirror section:

A high C/N ratio relating to a reproduction signal from a system lead-inarea SYLDI can be ensured and high reproduction reliability can beensured.

7) “L-H” organic dye recording film and light reflection factor rangefrom unrecorded area at the time of on-track:

A high C/N rate relating to a wobble detection signal in an unrecordedarea can be ensured, and high reproduction reliability relevant towobble address information can be ensured.

8) “L-H” organic dye recording film and wobble detection signalamplitude range:

A high C/N ratio relating to a wobble detection signal can be ensured,and high reproduction reliability relevant to wobble address informationcan be ensured.

<<Table of Contents>>

Chapter 0:Description of Relationship between Wavelength and the PresentEmbodiment

Wavelength used in the present embodiment.

Chapter 1:Description of Combination of Constituent Elements ofInformation Storage Medium in the Present Embodiment:

FIG. 1 shows an illustration of the contents of constituent elements ofthe information storage medium in the present embodiment.

Chapter 2: Description of Difference in reproduction signal betweenPhase Change Recording Film and Organic Dye Recording Film

2-1) Difference in Principle of Recording/Recording Film and Differencein Basic Concept Relating to Generation of Reproduction Signal . . . .Definition of λ_(max write)

2-2) Difference of Light Reflection Layer Shape in Pre-pit/Pre-grooveArea

Optical reflection layer shape (difference in spin coating andsputtering vapor deposition) and influence on a reproduction signal.

Chapter 3:Description of Characteristics of Organic Dye Recording Filmin the Present Embodiment

3-1) Problem(s) relevant to achievement of high density in write-oncetype recording film (DVD-R) using conventional organic dye material

3-2) Description of basic characteristics common to organic dyerecording films in the present embodiment:

Lower limit value of recording layer thickness, channel bit length/trackpitch in which advantageous effect is attained in the invention,repetitive playback enable count, optimal reproduction power,

Rate between groove width and land width . . . . Relationship withwobble address format

Relationship in recording layer thickness between groove section andland section

Technique of improving error correction capability of recordinginformation and combination with PRML

3-3) Recording characteristics common to organic dye recording films inthe present embodiment

Upper Limit Value of Optimal Recording Power

3-4) Description of characteristics relating to a “High to Low(hereinafter, abbreviated to as H-L)” recording film in the presentembodiment:

Upper Limit Value of Reflection Factor in Unrecorded Layer

Relationship between a value Of λ_(max write) and a value of λl_(max)(absorbance maximum wavelength at unrecorded/recorded position)

Relative values of reflection factor and degree of modulation atunrecorded/recorded position and light absorption values at reproductionwavelength . . . n·k range

Relationship in upper limit value between required resolutioncharacteristics and recording layer thickness

Chapter 4:Description of Reproducing Apparatus or Recording/ReproducingApparatus and Recording Condition/Reproducing Circuit

4-1) Description of structure and characteristics of reproducingapparatus or recording/reproducing apparatus in the present embodiment:Use wavelength range, NA value, and RIM intensity

4-2) Description of reproducing circuit in the present embodiment

4-3) Description of recording condition in the present embodiment

Chapter 5: Description of Specific Embodiments of Organic Dye RecordingFilm in the Present Embodiment

5-1) Description of characteristics relating to “L-H” recording film inthe present embodiment

Principle of recording and reflection factor and degree of modulation atunrecorded/recorded position

5-2) Characteristics of light absorption spectra relating to “L-H”recording film in the present embodiment:

Condition for setting maximum absorption wavelength λ_(max write), valueof Al₄₀₅ and a value of Ah₄₀₅

5-3) Anion portion: Azo metal complex+cation portion: Dye

5-4) Use of “copper” as azo metal complex+main metal:

Light absorption spectra after recorded is widen in a “H-L” recordingfilm, and is narrowed in a “L-H” recording film.

Upper limit value of maximum absorption wavelength change amount beforeand after recording:

A maximum absorption wavelength change amount before and after recordingis small, and absorbance at a maximum absorption wavelength changes.

Chapter 6: Description Relating to Pre-groove shape/pre-pit shape incoating type organic dye recording film and on light reflection layerinterface

6-1) Light reflection layer (material and thickness):

Thickness range and passivation structure . . . . Principle of recordingand countermeasures against degradation (Signal is degraded more easilythan substrate deformation or than cavity)

6-2) Description relating to pre-pit shape in coating type organic dyerecording film and on light reflection layer interface:

Advantageous effect achieved by widening track pitch/channel bit pitchin system lead-in area:

Reproduction signal amplitude value and resolution in system lead-inarea:

Rule on step amount at land portion and pre-pit portion in lightreflection layer 4-2:

6-3) Description relating to pre-groove shape in coating type organicdye recording film and on light reflection layer interface:

Rule on step amount at land portion and pre-groove portion in lightreflection layer 4-2:

Push-pull signal amplitude range:

Wobble signal amplitude range (combination with wobble modulationsystem)

Chapter 7: Description of First Next-Generation Optical Disk: HD DVDSystem (Hereinafter, Referred to as H Format):

Principle of recording and countermeasure against reproduction signaldegradation (Signal is degraded more easily than substrate deformationor than cavity):

Error Correction Code (ECC) structure, PRML (Partial Response MaximumLikelihood) System:

Relationship between a wide flat area in the groove and wobble addressformat.

In the write-once recording, overwriting is carried out in a VFO areawhich is non-data area.

Influence of DC component change in overwrite area is reduced. Inparticular, advantageous effect on “L-H” recording film is significant.

Chapter 8: Description of Second Next-Generation Optical Disk: B format

Principle of recording and countermeasures against reproduction signaldegradation (Signal is degraded more easily than substrate deformationor cavity).

Relationship between a wide flat area in the groove and wobble addressformat

In the write-once recording, overwriting is carried out in a VFO areawhich is a non-data area.

Influence of DC component change in overwrite area is reduced. Inparticular, advantageous effect in “L-H” recording film is significant.

Now, a description of the present embodiment will be given here.

Chapter 0:Description of Relationship Between Use Wavelength and thePresent Embodiment

As a write-once type optical disk obtained by using an organic dyematerial for a recording medium, there has been commercially available aCD-R disk using a recording/reproducing laser light source wavelength of780 nm and a DVD-R disk using a recording/reproducing laser light beamwavelength of 650 nm. Further, in a next-generation write-once typeinformation storage medium having achieved high density, it is proposedthat a laser light source wavelength for recording or reproducing, whichis close to 405 nm (namely, in the range of 355 nm to 455 nm), is usedin either of H format (D1) and B format (D2) of FIG. 1 described later.In a write-once type information storage medium using an organic dyematerial, recording/reproducing characteristics sensitively changes dueto a slight change of a light source wavelength. In principle, densityis increased in inverse proportion to a square of a laser light sourcewavelength for recording/reproducing, and thus, it is desirable that ashorter laser light source wavelength be used for recording/reproducing.However, for the above described reason, an organic dye materialutilized for a CD-R disk or a DVD-R disk cannot be used as a write-oncetype information storage medium for 405 nm. Moreover, because 405 nm isclose to an ultraviolet ray wavelength, there can easily occur adisadvantage that a recording material “which can be easily recordedwith a light beam of 405 nm”, is easily changed in characteristics dueto ultraviolet ray irradiation, lacking a long period stability.Characteristics are significantly different from each other depending onorganic dye materials to be used, and thus, it is difficult to determinethe characteristics of these dye materials in general. As an example,the foregoing characteristics will be described by way of a specificwavelength. With respect to an organic dye recording material optimizedwith a light beam of 650 nm in wavelength, the light to be used becomesshorter than 620 nm, recording/reproducing characteristics significantlychange. Therefore, in the case where a recording/reproducing operationis carried out with a light beam which is shorter than 620 nm inwavelength, there is a need for new development of an organic dyematerial which is optimal to a light source wavelength of recordinglight or reproducing light. An organic dye material of which recordingcan be easily carried out with a light beam shorter than 530 nm inwavelength easily causes characteristic degradation due to ultravioletray irradiation, lacking long period stability. In the presentembodiment, a description will be given with respect to an embodimentrelevant to an organic recording material suitable to use in close to405 nm. Namely, a description will be given with respect to anembodiment relating to an organic recording material which can be stablyused in the range of 355 nm to 455 nm in consideration of a fluctuationof a light emitting wavelength which depends on manufacturers ofsemiconductor laser light sources. That is, the scope of the presentembodiment corresponds to a light beam which is adapted to a lightsource of 620 nm in wavelength, and desirably, which is shorter than 530nm in wavelength (ranging from 355 nm to 455 nm in a definition in thenarrowest range).

In addition, the optical recording sensitivity due to light absorptionspectra of an organic dye material is also influenced by a recordingwavelength. An organic dye material suitable for long period stabilityis easily reduced in light absorbance relevant to a light beam which isshorter than 620 nm in wavelength. In particular, the light absorbanceis significantly lowered with respect to a light beam which is shorterthan 620 nm in wavelength, and in particular, is drastically reducedwith respect to a light beam which is shorter than 530 nm in wavelength.Therefore, in the case where recording is carried out with a laser lightbeam ranging from 355 nm to 455 nm in wavelength, which is the severestcondition, recording sensitivity is impaired because the lightabsorbance is low, and there is a need for a new design employing a newprinciple of recording as shown in the present embodiment.

The size of a focusing spot used for recording or reproducingapplication is reduced in proportion to a wavelength of a light beam tobe used. Therefore, from only a standpoint of the focusing spot size, inthe case where a wavelength is reduced to the above described value, anattempt is made to reduce a track pitch or channel bit length by awavelength component with respect to a current DVD-R disk (usewavelength: 650 nm) which is a conventional technique. However, asdescribed later in “3-2-A] Scope requiring application of techniqueaccording to the present embodiment”, as long as a principle ofrecording in a conventional write-once type information storage mediumsuch as a DVD-R disk is used, there is a problem that a track pitch or achannel bit length cannot be reduced. A track pitch or a channel bitlength can be reduced in proportion to the above described wavelength byutilizing a technique devised in the present embodiment described below.

Chapter 1: Description of Combination of Constituent Elements ofInformation Storage Medium in the Present Embodiment

In the present embodiment, there exists a great technical feature inthat an organic recording medium material (organic dye material) adaptedto a light source of 620 nm or less in wavelength has been devised. Suchan organic recording medium (organic dye material) has a uniquecharacteristic (Low to High characteristic) that a light reflectionfactor increases in a recording mark, which does not exist in aconventional CD-R disk or a DVD-R disk. Therefore, a technical featureof the present embodiment and a novel effect attained thereby occurs ina structure, dimensions, or format (information recording format)combination of the information storage medium which produces moreeffectively the characteristics of the organic recording material(organic dye materials) shown in the present embodiment. FIG. 1 shows acombination, which produces a new technical feature and advantageouseffect in the present embodiment. That is the information storage mediumin the present embodiment has the following constituent elements:

A] an organic dye recording film;

B] a pre-format (such as pre-groove shape/dimensions or pre-pitshape/dimensions);

C] a wobble condition (such as wobble modulation method and wobblechange shape, wobble amplitude, and wobble allocating method); and

D] a format (such as format for recording data which is to be recordedor which has been recorded in advance in information storage medium).

Specific embodiments of constituent elements correspond to the contentsdescribed in each column of FIG. 1. A technical feature and a uniqueadvantageous effect of the present embodiment occur in combination ofthe specific embodiments of the constituent elements shown in FIG. 1.Hereinafter, a description will be given with respect to a combinationstate of individual embodiments at a stage of explaining theembodiments. With respect to constituent elements, which do not specifya combination, it denotes that the following characteristics areemployed:

A5) an arbitrary coating recording film;

B3) an arbitrary groove shape and an arbitrary pit shape;

C4) an arbitrary modulation system;

C6) an arbitrary amplitude amount; and

D4) an arbitrary recording method and a format in a write-once medium.

Chapter 2:Description of Difference in Reproduction Signal Between PhaseChange Recording Film and Organic Dye Recording Film

2-1) Difference in Principle of Recording/Recording Film and Differencein Basic Concept Relating to Generation of Reproduction Signal

FIG. 2A shows a standard phase change recording film structure (mainlyused for a rewritable-type information storage medium), and FIG. 2Bshows a standard organic dye recording film structure (mainly used for awrite-once type information storage medium). In the description of thepresent embodiment, a whole recording film structure excludingtransparent substrates 2-1 and 2-2 shown in FIGS. 2A and 2B (includinglight reflection layers 4-1 and 4-2) is defined as a “recording film”,and is discriminated from recording layers 3-1 and 3-2 in which arecording material is disposed. With respect to a recording materialusing a phase change, in general, an optical characteristic changeamount in a recorded area (in a recording mark) and an unrecorded area(out of a recording mark) is small, and thus, there is employed anenhancement structure for enhancing a relative change rate of areproduction signal. Therefore, in a phase change recording filmstructure, as shown in FIG. 2A, an undercoat intermediate layer 5 isdisposed between the transparent substrate 2-1 and a phase change typerecording layer 3-1, and an upper intermediate layer 6 is disposedbetween the light reflection layer 4-2 and the phase change typerecording layer 3-1. In the invention, as a material for the transparentsubstrates 2-1 and 2-2, there is employed a polycarbonate PC or anacrylic PMMA (poly methyl methacrylate) which is a transparent plasticmaterial. A center wavelength of a laser light beam 7 used in thepresent embodiment is 405 nm, and refractive index n₂₁, n₂₂ of thepolycarbonate PC at this wavelength is close to 1.62. Standardrefractive index n₃₁ and absorption coefficient k₃₁ in 405 nm at GeSbTe(germanium antimony tellurium) which is most generally used as a phasechange type recording material are n₃₁≈1.5 and k₃₁≈2.5 in a crystallinearea, whereas they are n₃₁=≈2.5 and k₃₁≈1.8 in an amorphous area. Thus,a refractive index (in the amorphous area) of a phase change typerecording medium is different from a refractive index of the transparentsubstrate 2-1, and reflection of a laser light beam 7 on an interfacebetween the layers is easily occurred in a phase change recording filmstructure. As described above, for the reasons why (1) a phase changerecording film structure takes an enhancement structure; and (2) arefractive index difference between the layers is great or the like, alight reflection amount change at the time of reproduction from arecording mark recorded in a phase change recording film (a differentialvalue of a light reflection amount from a recording mark and a lightreflection amount from an unrecorded area) can be obtained as aninterference result of multiple reflection light beams generated on aninterface between the undercoat intermediate layer 5, the recordinglayer 3-1, the upper intermediate layer 6, and the light reflectionlayer 4-2. In FIG. 2A, although the laser light beam 7 is apparentlyreflected on an interface between the undercoat intermediate layer 5 andthe recording layer 3-1, an interface between the recording layer 3-1and the upper intermediate layer 6, and an interface between the upperintermediate layer 6 and the light reflection layer 4-2, in actuality, areflection light amount change is obtained as an interference resultbetween a plurality of multiple reflection light beams.

In contrast, an organic dye recording film structure takes a very simplelaminate structure made of an organic dye recording layer 3-2 and alight reflection layer 4-2. An information storage medium (optical disk)using this organic dye recording film is called a write-once typeinformation storage medium, which enables only one time of recording.However, unlike a rewritable-type information storage medium using thephase change recording medium, this medium cannot carry out an erasingprocess or a rewriting process of information which has been recordedonce. A refractive index at 405 nm of a general organic dye recordingmaterial is often close to n₃₂≈1.4 (n₃₂=1.4 to 1.9 in the refractiveindex range at 405 nm of a variety of organic dye recording materials)and an absorption coefficient is often close to k₃₂≈0.2 (k₃₂≈0.1 to 0.2in the absorption coefficient range at 405 nm of a variety of organicdye recording materials). Because a refractive index difference betweenthe organic dye recording material and the transparent substrate 2-2 issmall, there hardly occurs a light reflection amount on an interfacebetween the recording layer 3-2 and the transparent substrate 2-2.Therefore, an optical reproduction principle of an organic colorrecording film (reason why a reflection light amount change occurs) isnot “multiple interference” in a phase change recording film, and a mainfactor is a “light amount loss (including interference) midway of anoptical path with respect to the laser light beam 7 which comes backafter being reflected in the light reflection layer 4-2”. Specificreasons which cause a light amount loss midway of an optical pathinclude an “interference phenomenon due to a phase difference partiallycaused in the laser light 7” or an “optical absorption phenomenon in therecording layer 3-2”. The light reflection factor of the organic dyerecording film in an unrecorded area on a mirror surface on which apre-groove or a pre-pit does not exist is featured to be simply obtainedby a value obtained by subtracting an optical absorption amount when therecording layer 3-2 is passed from the light reflection factor of thelaser light beam 7 in the light reflection layer 4-2. As describedabove, this film is different from a phase change recording film whoselight reflection factor is obtained by calculation of “multipleinterference”.

First, a description will be given with respect to a principle ofrecording, which is used in a current DVD-R disk as a conventionaltechnique. In the current DVD-R disk, when a recording film isirradiated with the laser light beam 7, the recording layer 3-2 locallyabsorbs energy of the laser light beam 7, and becomes hot. If a specifictemperature is exceeded, the transparent substrate 2-2 is locallydeformed. Although a mechanism, which induces deformation of thetransparent substrate 2-2, is different depending on manufacturers ofDVD-R disks, it is said that this mechanism is caused by:

1) local plastic deformation of the transparent substrate 2-2 due togasification energy of the recording layer 3-2; and

2) transmission of a heat from the recording layer 3-2 to thetransparent substrate 2-2 and local plastic deformation of thetransparent substrate 2-2 due to the heat.

If the transparent substrate 2-2 is locally plastically deformed, therechanges an optical distance of the laser light beam 7 reflected in thelight reflection layer 4-2 through the transparent substrate 2-2, thelaser light beam 7 coming back through the transparent substrate 2-2again. A phase difference occurs between the laser light beam 7 from arecording mark, the laser light beam coming back through a portion ofthe locally plastically deformed transparent substrate 2-2, and a laserlight beam 7 from the periphery of the recording mark, the laser lightbeam coming back through a portion of a transparent substrate 2-2 whichis not deformed, and thus, a light amount change of reflection lightbeam occurs due to interference between these light beams. In addition,in particular, in the case where the above described mechanism of (1)has occurred, a change of a substantial refractive index n₃₂ produced bycavitation of the inside of the recording mark in the recording layer3-2 due to gasification (evaporation), or alternatively, a change of arefractive index n₃₂ produced due to thermal decomposition of an organicdye recording material in the recording mark, also contributes to theabove described occurrence of a phase difference. In the current DVD-Rdisk, until the transparent substrate 2-2 is locally deformed, there isa need for the recording layer 3-2 becoming hot (i.e., at a gasificationtemperature of the recording layer 3-2 in the above described mechanismof (1) or at an internal temperature of the recording layer 3-2 requiredfor plastically reforming the transparent substrate 2-2 in the mechanismof (2)) or there is a need for a part of the recording layer 3-2becoming hot in order to cause thermal decomposition or gasification(evaporation). In order to form a recording mark, there is a need forlarge amount of power of the laser light beam 7.

In order to form the recording mark, there is a necessity that therecording layer 3-2 can absorb energy of the laser light beam 7 at afirst stage. The light absorption spectra in the recording layer 3-2influence the recording sensitivity of an organic dye recording film. Aprinciple of light absorption in an organic dye recording material whichforms the recording layer 3-2 will be described with reference to (A3)of the present embodiment.

FIG. 3 shows a specific structural formula of the specific contents“(A3) azo metal complex+Cu” of the constituent elements of theinformation storage medium shown in FIG. 1. A circular periphery areaaround a center metal M of the azo metal complex shown in FIG. 3 isobtained as a light emitting area 8. When a laser light beam 7 passesthrough this light emitting area 8, local electrons in this lightemitting area 8 resonate to an electric field change of the laser lightbeam 7, and absorbs energy of the laser light beam 7. A value convertedto a wavelength of the laser light beam with respect to a frequency ofan electric field change at which these local electrons resonate mostand easily absorbs the energy is called a maximum absorption wavelength,and is represented by λ_(max). As a range of the light emitting area 8(resonation range) as shown in FIG. 3 increases, the maximum absorptionwavelength λ_(max) is shifted to the long wavelength side. In addition,in FIG. 3, the localization range of local electrons around the centermetal M (how large the center metal M can attract the local electrons tothe vicinity of the center) is changed by changing atoms of the centermetal M, and the value of the maximum absorption wavelength λ_(max)changes.

Although it can be predicted that the light absorption spectra of theorganic dye recording material in the case where there exists only onelight emitting area 8 which is absolute 0 degree at a temperature andhigh in purity draws narrow linear spectra in close to a maximumabsorption wavelength λ_(max), the light absorption spectra of a generalorganic recording material including impurities at a normal temperature,and further, including a plurality of light absorption areas exhibit awide light absorption characteristic with respect to a wavelength of alight beam around the maximum absorption wavelength λ_(max).

FIG. 4 shows an example of light absorption spectra of an organic dyerecording material used for a current DVD-R disk. In FIG. 4, awavelength of a light beam to be irradiated with respect to an organicdye recording film formed by coating an organic dye recording materialis taken on a horizontal axis, and absorbance obtained when an organicdye recording film is irradiated with a light beam having a respectivewavelength is taken on a vertical axis. The absorbance used here is avalue obtained by entering a laser light beam having incident intensityIo from the side of the transparent substrate 2-2 with respect to astate in which a write-once type information storage medium has beencompleted (or alternatively, a state in which the recording layer 3-2has been merely formed on the transparent substrate 2-2 (a state thatprecedes forming of the optical reflection layer 4-2 with respect to astructure of FIG. 2B)), and then, measuring reflected laser lightintensity Ir (light intensity It of the laser light beam transmittedfrom the side of the recording layer 3-2). The absorbance Ar (At) isrepresented by:Ar≡−log₁₀(Ir/Io)  (A-1)Ar≡−log₁₀(It/Io)  (A-2)

Unless otherwise specified, although a description will be givenassuming that the absorbance denotes absorbance Ar of a reflection shapeexpressed by formula (A-1), it is possible to define absorbance At of atransmission shape expressed by formula (A-2) without being limitedthereto in the present embodiment. In the embodiment shown in FIG. 4,there exist a plurality of light absorption areas, each of whichincludes the light emitting area 8, and thus, there exist a plurality ofpositions at which the absorbance becomes maximal. In this case, thereexist a plurality of maximum absorption wavelength λ_(max) when theabsorbance takes a maximum value. A wavelength of the recording laserlight in the current DVD-R disk is set to 650 nm. In the case wherethere exist a plurality of the maximum absorption wavelengths λ_(max) inthe present embodiment, a value of the maximum absorption wavelengthλ_(max) which is the closest to the wavelength of the recording laserlight beam becomes important. Therefore, only in the description of thepresent embodiment, the value of the maximum absorption wavelengthλ_(max) set at a position which is the closest to the wavelength of therecording laser light beam is defined as “λ_(max) write”; and isdiscriminated from another λ_(max) (λ_(max 0))

2-2) Difference of light reflection layer shape in pre-pit/pre-groovearea

FIGS. 5A and 5B each show a comparison in shape when a recording film isformed in a pre-pit area or a pre-groove area 10. FIG. 5A shows a shaperelevant to a phase change recording film. In the case of forming any ofthe undercoat intermediate layer 5, the recording layer 3-1, the upperintermediate layer 6, and the light reflection layer 4-1 as well, any ofmethods of sputtering vapor deposition, vacuum vapor deposition, or ionplating is used in vacuum. As a result, in all of the layers,irregularities of the transparent substrate 2-1 are duplicatedcomparatively faithfully. For example, in the case where a sectionalshape in the pre-pit area or pre-groove area 10 of the transparentsubstrate 2-1 is rectangular or trapezoidal, the sectional shape of therecording layer 3-1 and the light reflection layer 4-1 each is alsorectangular or trapezoidal.

FIG. 5B shows a general recording film sectional shape of a currentDVD-R disk which is a conventional technique as a recording film in thecase where an organic dye recording film has been used. In this case, asa method for forming the recording film 3-2, there is used a methodcalled spin coating (or spinner coating) which is completely differentfrom that shown in FIG. 5A. The spin coating used here denotes a methodfor dissolving in an organic solvent an organic dye recording materialwhich forms the recording layer 3-2; applying a coating onto thetransparent substrate 2-2; followed by rotating the transparentsubstrate 2-2 at a high speed to spread a coating agent to the outerperiphery side of the transparent substrate 2-2 by a centrifugal force;and gasifying the organic solvent, thereby forming the recording layer3-2. Using this method, a process for coating the organic solvent isused, and thus, a surface of the recording layer 3-2 (an interface withthe light reflection layer 2-2) is easily flattened. As a result, thesectional shape on the interface between the light reflection layer 2-2and the recording layer 3-2 is obtained as a shape which is differentfrom the shape of the surface of the transparent substrate 2-2 (aninterface between the transparent substrate 2-2 and the recording layer3-2). For example, in a pre-groove area in which the sectional shape ofthe surface of the transparent substrate 2-2 (an interface between thetransparent substrate 2-2 and the recording layer 3-2) is rectangular ortrapezoidal, the sectional shape on the interface between the lightreflection layer 2-2 and the recording layer 3-2 is formed in asubstantially V-shaped groove shape. In a pre-pit area, the abovesectional shape is formed in a substantially conical side surface shape.Further, at the time of spin coating, an organic solvent is easilycollected at a recessed portion, and thus, the thickness Dg of therecording layer 3-2 in the pre-pit area or pre-groove area 10 (i.e., adistance from a bottom surface of the pre-pit area or pre-groove area toa position at which an interface relevant to the light reflection layer2-2 becomes the lowest) is larger than the thickness Dl in a land area12 (Dg>Dl). As a result, an amount of irregularities on an interfacebetween the transparent substrate 2-2 and the recording area 3-2 in thepre-pit area or pre-groove area 10 becomes substantially smaller than anamount of irregularities on the transparent substrate 2-2 and therecording layer 3-2.

As described above, the shape of irregularities on the interface betweenthe light reflection layer 2-2 and the recording layer 3-2 becomes bluntand an amount of irregularities becomes significantly small. Thus, inthe case where the shape and dimensions of irregularities on a surfaceof the transparent substrate 2 (pre-pit area or pre-groove area 10) areequal to each other depending on a difference in method for forming arecording film, the diffraction intensity of the reflection light beamfrom the organic dye recording film at the time of laser lightirradiation is degraded more significantly than the diffractionintensity of the reflection light beam from the phase change recordingfilm. As a result, in the case where the shape and dimensions ofirregularities on the surface of the transparent substrate 2 (pre-pitarea or pre-groove area 10) are equal to each other, as compared withuse of the phase change recording film, use of the conventional organicdye recording film is disadvantageously featured in that:

1) a degree of modulation of a light reproduction signal from thepre-pit area is small, and signal reproduction reliability from thepre-pit area is poor;

2) a sufficiently large track shift detecting signal is hardly obtainedin accordance with a push-pull technique from the pre-groove area; and

3) a sufficient large wobble detecting signal is hardly obtained in thecase where wobbling occurs in the pre-groove area.

In addition, in a DVD-R disk, specific information such as addressinformation is recorded in a small irregular (pit) shape in a land area,and thus, a width Wl of the land area 12 is larger than a width Wg ofthe pre-pit area or pre-groove area 10 (Wg>Wl).

Chapter 3: Description of Characteristics of Organic Dye Recording Filmin the Present Embodiment

3-1) Problem(s) relevant to achievement of high density in write-oncetype recording film (DVD-R) using conventional organic dye material

As has been described in “2-1) Difference in recordingprinciple/recording film structure and difference in basic conceptrelating to generation of reproducing signal”, a general principle ofrecording of a current DVD-R and CD-R, which is a write-once typeinformation storage medium using a conventional organic dye materialincludes “local plastic deformation of transparent substrate 2-2” or“local thermal decomposition or “gasification” in recording layer 3-2”.FIGS. 6A and 6B each show a plastic deformation state of a specifictransparent substrate 2-2 at a position of a recording mark 9 in awrite-once type information storage medium using a conventional organicdye material. There exist two types of typical plastic deformationstates. There are two cases, i.e., a case in which, as shown in FIG. 6A,a depth of a bottom surface 14 of a pre-groove area at the position ofthe recording mark 9 (an amount of step relevant to an adjacent landarea 12) is different from a depth of a bottom surface of a pre-groovearea 11 in an unrecorded area (in the example shown in FIG. 6A, thedepth of the bottom surface 14 in the pre-groove area at the position ofthe recording mark 9 is shallower than that in the unrecorded area); anda case in which, as shown in FIG. 6B, a bottom surface 14 in apre-groove area at the position of the recording mark 9 is distorted andis slightly curved (the flatness of the bottom surface 14 is distorted:In the example shown in FIG. 6B, the bottom surface 14 in the pre-groovearea at the position of the recording mark 9 is slightly curved towardthe lower side). Both of these cases are featured in that a plasticdeformation range of the transparent substrate 2-2 at the position ofthe recording mark 9 covers a wide range. In the current DVD-R diskwhich is a conventional technique, a track pitch is 0.74 μm, and achannel bit length is 0.133 μm. In the case of a large value of thisdegree, even if the plastic deformation range of the transparentsubstrate 2-2 at the position of the recording mark 9 covers a widerange, comparatively stable recording and reproducing processes can becarried out.

However, if the track pitch is narrower than 0.74 μm described above,the plastic deformation range of the transparent substrate 2-2 at theposition of the recording mark 9 covers a wide range, and thus, theadjacent tracks are adversely affected, and the recording mark 9 of theexisting adjacent track is substantially erased (cannot be reproduced)due to a “cross-write” or overwrite in which the recording mark 9 widensto the adjacent tracks. In addition, in a direction (circumferentialdirection) along the tracks, if the channel bit length is narrower than0.133 μm, there occurs a problem that inter-code interference appears;an error rate at the time of reproduction significantly increases; andthe reliability of reproduction is lowered.

3-2) Description of basic characteristics common to organic dyerecording film in the present embodiment

3-2-A] Range requiring application of technique according to the presentembodiment

As shown in FIGS. 6A and 6B, in a conventional write-once typeinformation storage medium including plastic deformation of thetransparent substrate 2-2 or local thermal decomposition or gasificationphenomenon in the recording film 3-2, a description will be given belowwith respect to what degree of track pitch is narrowed when an adverseaffect appears or what degree of channel pit length is narrowed when anadverse effect appears and a result obtained after technical discussionhas been carried out with respect to a reason for such an adverseeffect. A range in which an adverse effect starts appearing in the caseof utilizing the conventional principle of recording indicates a range(suitable for the achievement of high density) in which advantageouseffect is attained due to a novel principle of recording shown in thepresent embodiment.

1) Condition of thickness Dg of recording layer 3-2

When an attempt is made to carry out thermal analysis in order totheoretically identify a lower limit value of an allowable channel bitlength or a lower limit value of allowable track pitch, a range of thethickness Dg of a recording layer 3-2 which can be substantiallythermally analyzed becomes important. In a conventional write-once typeinformation storage medium (CD-R or DVD-R) including plastic deformationof the transparent substrate 2-2 as shown in FIGS. 6A and 6B, withrespect to a change of light reflection amount in the case where aninformation reproduction focusing spot is provided in the recording mark8 and in the case where the spot is in an unrecorded area of therecording layer 3-2, the largest factor is “an interference effect dueto a difference in optical distance in the recording mark 9 and inunrecorded area”. In addition, a difference in its optical difference ismainly caused by “a change of the thickness Dg of a physical recordinglayer 3-2 due to plastic deformation of the transparent substrate 2-2 (aphysical distance from an interface between the transparent substrate2-2 and the recording layer 3-2 to an interface between the recordinglayer 3-2 and a light reflection layer 4-2) and “a change of refractiveindex n₃₂ of the recording layer 3-2 in the recording mark 9”.Therefore, in order to obtain a sufficient reproduction signal (changeof light reflection amount) between the recording mark 9 and theunrecorded area, when a wavelength in vacuum of laser light beam isdefined as λ, it is necessary for the value of the thickness 3-2 in theunrecorded area has a size to some extent as compared with λ/n₃₂. Ifnot, a difference (phase difference) in optical distance between therecording mark 9 and the unrecorded area does not appear, and lightinterference effect becomes small. In reality, a minimum condition:Dg≧λ/8n ₃₂  (1)

must be met, and desirably, a condition that:Dg≧λ/4n ₃₂  (2)

must be met.

At a time point of current discussion, the vicinity of λ=405 nm isassumed. A value of refractive index n₃₂ of an organic dye recordingmaterial at 405 nm ranges from 1.3 to 2.0. Therefore, as a result ofsubstituting n₃₂=2.0 in formula (1), it is conditionally mandatory thata value of the thickness Dg of the recording layer 3-2 is:Dg≧25 nm  (3)

Here, discussion is made with respect to a condition when an organic dyerecording layer of a conventional write-once type information storagemedium (CD-R or DVD-R) including plastic deformation of the transparentsubstrate 2-2 has been associated with a light beam of 405 nm. Asdescribed later, in the present embodiment, although a description isgiven with respect to a case in which plastic deformation of thetransparent substrate 2-2 does not occur and a change of an absorptioncoefficient k₃₂ is a main factor of a principle of recording, it isnecessary to carry out track shift detection by using a DPD(Differential Phase Detection) technique from the recording mark 9, andthus, in reality, the change of the refractive index n₃₂ is caused inthe recording mark 9. Therefore, the condition for formula (3) becomes acondition, which should be met, in the present embodiment in whichplastic deformation of the transparent substrate 2-2 does not occur.

From another point of view as well, the range of the thickness Dg can bespecified. In the case of a phase change recording film shown in FIG.5A, when a refractive index of the transparent substrate is n₂₁, a stepamount between a pre-pit area and a land area is λ/(8n₂₁) when thelargest track shift detection signal is obtained by using a push-pulltechnique. However, in the case of an organic dye recording film shownin FIG. 5B, as described previously, the shape on an interface betweenthe recording layer 3-2 and the light reflection layer 4-2 becomesblunt, and a step amount becomes small. Thus, it is necessary toincrease a step amount between a pre-pit area and a land area on thetransparent substrate 2-2 more significantly than λ/(8n₂₂). For example,the refractive index at 405 nm in the case where polycarbonate has beenused as a material for the transparent substrate 2-2 is n₂₂≈1.62, andthus, it is necessary to increase a step amount between the pre-pit areaand the land area more significantly than 31 nm. In the case of using aspin coating technique, if the thickness Dg of the recording layer 3-2in the pre-groove area is greater than a step amount between the pre-pitarea and the land area on the transparent substrate 2-2, there is adanger that thickness D1 of the recording layer 3-2 in a land area 12 iseliminated. Therefore, from the above described discussion result, it isnecessary to meet a condition that:Dg≧31 nm  (4)

The condition for formula (4) is also a condition, which should be metin the present embodiment in which plastic deformation of thetransparent substrate 2-2 does not occur. Although conditions for thelower limit values have been shown in formulas (3) and (4), the valueDg≈60 nm obtained by substituting n₃₂=1.8 for an equal sign portion informula (2) has been utilized as the thickness Dg of the recording layer3-2 used for thermal analysis.

Then, assuming polycarbonate used as a standard material of thetransparent substrate 2-2, 150° C. which is a glass transitiontemperature of polycarbonate has been set as an estimate value of athermal deformation temperature at the side of the transparent substrate2-2. For discussion using thermal analysis, a value of k₃₂=0.1 to 0.2has been assumed as a value of an absorption coefficient of the organicdye recording film 3-2 at 405 nm. Further, discussion has been made withrespect to a case in which an NA value of a focusing objective lens andan incident light intensity distribution when an objective lens ispassed is NA=60 and H format ((D1):NA=0.65 in FIG. 1) and B format((D2):NA=0.85 in FIG. 1) which is assumed condition in a conventionalDVD-R format.

2) Condition for lower limit value of channel bit length

A check has been made for a lengthwise change in a direction along atrack of an area reaching a thermal deformation temperature at the sideof a transparent substrate 2-2 which comes into contact with a recordinglayer 3-2 when recording power has been changed. Discussion has beenmade with respect to a lower limit value of an allowable channel bitlength considering a window margin at the time of reproduction. As aresult, if the channel bit length is slightly lower than 105 nm, it isconsidered that a lengthwise change in a direction along a track in anarea which reaches the thermal deformation temperature at the side ofthe transparent substrate 2-2 occurs according to the slight change ofrecording power, and a sufficient window margin cannot be obtained. Ondiscussion of thermal analysis, an analogous tendency is shown in thecase where the NA value is any one of 0.60, 0.65, and 0.85. Although afocusing spot size is changed by changing the NA value, a possibilitycause is believed to be that a thermal spreading range is wide (agradient of a temperature distribution at the side of the transparentsubstrate 2-2 which comes into contact with the recording layer 3-2) iscomparatively gentle). In the above thermal analysis, the temperaturedistribution at the side of the transparent substrate 2-2 which comesinto contact with the recording layer 3-2 is discussed, and thus, aneffect of the thickness Dg of the recording layer 3-2 does not appear.

Further, in the case where a shape change of the transparent substrate3-3 shown in FIGS. 6A and 6B occurs, a boundary position of a substratedeformation area blurs (is ambiguous), and thus, a window margin islowered more significantly. When a sectional shape of an area in whichthe recording mark 9 is formed is observed by an electron microscope, itis believed that a blurring amount of the boundary position of thesubstrate deformation area increases as the value of the thickness Dg ofthe recording layer 3-2 increases. With respect to the effect of thethermal deformation area length due to the above recording power change,in consideration of the blurring of the boundary position of thissubstrate deformation area, it is considered necessary that the lowerlimit value of the channel bit length allowed for allocation of asufficient window margin is in order of two times of the thickness Dg ofthe recording layer 3-2, and it is desirable that the lower limit valueis greater than 120 nm.

In the foregoing, a description has been principally given with respectto discussion using thermal analysis in the case where thermaldeformation of the transparent substrate 2-2 occurs. There also exists acase in which plastic deformation of the transparent substrate 2-2 isvery small as another principle of recording (mechanism of forming therecording mark 9) in a conventional write-once type information storagemedium (CD-R or DVD-R) and thermal deformation or gasification(evaporation) of the organic dye recording material in the recordinglayer 3-2 mainly occurs. Thus, an additional description will be givenwith respect to such a case. Although the gasification (evaporation)temperature of the organic dye recording material is different dependingon the type of the organic dye material, in general, the temperatureranges 220° C. to 370° C., and a thermal decomposition temperature islower than this range. Although a glass transition temperature 150° C.of a polycarbonate resin has been presumed as an arrival temperature atthe time of substrate deformation in the above discussion, a temperaturedifference between 150° C. and 220° C. is small, and, when thetransparent substrate 2-2 reaches 150° C., the inside of the recordinglayer 3-2 exceeds 220° C. Therefore, although there exists an exceptiondepending on the type of the organic recording material, even in thecase where plastic deformation of the transparent substrate 2-2 is verysmall and thermal decomposition or gasification (evaporation) of theorganic dye recording material in the recording layer mainly occurs,there is obtained a result which is substantially identical to the abovediscussion result.

When the discussion result relating to the above channel bit length issummarized, in the conventional write-once type information storagemedium (CD-R or DVD-R) including plastic deformation of the transparentsubstrate 2-2, it is considered that, when a channel bit length isnarrower than 120 nm, the lowering of a window margin occurs, andfurther, if the length is smaller than 105 nm, stable reproductionbecomes difficult. That is, when the channel bit is smaller than 120 nm(105 nm), advantageous effect is attained by using a novel principle ofrecording shown in the present embodiment.

3) Condition for lower limit value of track pitches

When a recording layer 3-2 is exposed at recording power, energy isabsorbed in the recording layer 3-2, and a high temperature is obtained.In a conventional write-once type information storage medium (CD-R orDVD-R), it is necessary to absorb energy in the recording layer 3-2until the transparent substrate 3-2 has reached a thermal deformationtemperature. A temperature at which a structural change of the organicdye recording material occurs in the recording layer 3-2 and a value ofa refractive index n₃₂ or an absorption coefficient k₃₂ starts itschange is much lower than an arrival temperature for the transparentsubstrate 2-2 to start thermal deformation. Therefore, the value of therefractive index n₃₂ or absorption coefficient k₃₂ changes in acomparatively wide range in the recording layer 3-2 at the periphery ofa recording mark 9, which is thermal deformed at the side of thetransparent substrate 2-2, and this change seems to cause “cross-write”or “cross-erase” for the adjacent tracks. It is possible to set a lowerlimit value of track pitch in which “cross-write” or “cross-erase” doesnot occur with the width of an area which reaches a temperature whichchanges the refractive index n₃₂ or absorption coefficient k₃₂ in therecording layer 3-2 when the transparent substrate 2-2 exceeds a thermaldeformation temperature. From the above point of view, it is consideredthat “cross-write” or “cross-erase” occurs in location in which thetrack pitch is equal to or smaller than 500 nm. Further, inconsideration of an effect of warping or inclination of an informationstorage medium or a change of recording power (recording power margin),it can be concluded difficult to set the track pitch to 600 nm or lessin the conventional write-once type information storage medium (CD-R orDVD-R) in which energy is absorbed in the recording layer 3-2 until thetransparent substrate 2-2 has reached a thermal deformation temperature.

As described above, even if the NA value is changed from 0.60, 0.65, andthen, to 0.85, substantially similar tendency is shown because thegradient of the temperature distribution in the (peripheral recordinglayer 3-2 when the transparent substrate 2-2 has reached a thermaldeformation temperature at a center part is comparatively gentle, andthe thermal spread range is wide. In the case where plastic deformationof the transparent substrate 2-2 is very small and thermal decompositionor gasification (evaporation) of the organic dye recording material inthe recording layer 3-2 mainly occurs as another principle of recording(mechanism of forming the recording mark 9) in the conventionalwrite-once type information storage medium (CD-R or DVD-R), as has beendescribed in the section “(2) Condition for lower limit value of channelbit”, the value of track pitch at which “cross-write” or “cross-erase”starts is obtained as a substantially analogous result. For the abovedescribed reason, advantageous effect is attained by using a novelprinciple of recording shown in the present embodiment when the trackpitch is set to 600 nm (500 nm) or lower.

3-2-B] Basic characteristics common to organic dye recording material inthe invention

As described above, in the case where plastic deformation of thetransparent substrate 2-2 is very small and thermal decomposition orgasification (evaporation) of the organic dye recording material in therecording layer 3-2 mainly occurs as another principle of recording(mechanism of forming the recording mark 9) in the conventionalwrite-once type information storage medium (CD-R or DVD-R), there occursa problem that a channel bit length or track pitches cannot be narrowedbecause the inside of the recording layer 3-2 or a surface of thetransparent substrate 2-2 reaches a high temperature at the time offorming the recording mark 9. In order to solve the above describedproblem, the present embodiment is primarily featured in “inventiveorganic dye material” in which “a local optical characteristic change inthe recording layer 3-2, which occurs at a comparatively lowtemperature, is a principle of recording” and “setting environment(recording film structure or shape) in which the above principle ofrecording easily occurs without causing a substrate deformation andgasification (evaporation) in the recording layer 3-2. Specificcharacteristics of the present embodiment can be listed below.

α] Optical characteristic changing method inside of recording layer 3-2

Chromogenic Characteristic Change

Change of light absorption sectional area due to qualitative change oflight emitting area 8 (FIG. 3) or change of molar molecule lightabsorption coefficient

The light emitting area 8 is partially destroyed or the size of thelight emitting area 8 changes, whereby a substantial light absorptionsectional area changes. In this manner, an amplitude (absorbance) at aposition of λ_(max write) changes in the recording mark 9 while aprofile (characteristics) of light absorption spectra (FIG. 4) itself ismaintained.

Change of electronic structure (electron orbit) relevant to electronswhich contribute to a chromogenic phenomenon

Change of light absorption spectra (FIG. 4) based on discoloring actiondue to cutting of local electron orbit (dissociation of local molecularbonding) or change of dimensions or structure of light emitting area 8(FIG. 3)

Intra-Molecular (Inter-Molecular) Change of Orientation or Array

Optical characteristic change based on orientation change in azo metalcomplex shown in FIG. 3, for example

Molecular Structure Change in Molecule

For example, discussion is made with respect to an organic dye materialwhich causes either of dissociation between anion portion and cationportion, thermal decomposition of either of anion portion and cationportion, and a tar phenomenon that a molecular structure itself isdestroyed, and carbon atoms are precipitated (denaturing to black coaltar). As a result, the refractive index n₃₂ or absorption (coefficientk₃₂ in the recording mark 9 is changed with respect to an unrecordedarea, enabling optical reproduction.

β] Setting recording film structure or shape, making it easy to stablycause an optical characteristic change of [α] above:

The specific contents relating to this technique will be described indetail in the section “3-2-C] Ideal recording film structure which makesit easy to cause a principle of recording shown in the presentembodiment” and subsequent.

γ] Recording power is reduced in order to form recording mark in a statein which inside of recording layer or transparent substrate surface iscomparatively low at temperature

The optical characteristic change shown in [α] above occurs at atemperature lower than a deformation temperature of the transparentsubstrate 2-2 or a gasification (evaporation) temperature in therecording layer 3-2. Thus, the exposure amount (recording power) at thetime of recording is reduced to prevent the deformation temperature frombeing exceeded on the surface of the transparent substrate 2-2 or thegasification (evaporation) temperature from being exceeded in therecording layer 3-2. The contents will be described later in detail inthe section “3-3) Recording characteristics common to organic dyerecording layer in the present embodiment”. In addition, in contrast, itbecomes possible to determine whether or not the optical characteristicchange shown in [α] above occurs by checking a value of the optimalpower at the time of recording.

δ] Electron structure in a light emitting area is stabilized, andstructural decomposition relevant to ultraviolet ray or reproductionlight irradiation is hardly generated

When ultraviolet ray is irradiated to the recording layer 3-2 orreproduction light is irradiated to the recording layer 3-2 at the timeof reproduction, a temperature size in the recording layer 3-2 occurs.There is a request for a seemingly contradictory performance thatcharacteristic degradation relevant to such a temperature rise isprevented and recording is carried out at a temperature lower than asubstrate deformation temperature or a gasification (evaporation)temperature in the recording layer 3-2. In the present embodiment, theabove described seemingly contradictory performance is ensured by“stabilizing an electron structure in a light emitting area”. Thespecific technical contents will be described in “Chapter 4 SpecificDescription of Embodiments of Organic Dye Recording Film in the PresentEmbodiment”.

ε] Reliability of reproduction information is improved for a case inwhich reproduction signal degradation due to ultraviolet ray orreproduction light irradiation occurs

In the present embodiment, although a technical contrivance is made for“stabilizing an electron structure in a light emitting area”, thereliability of the recording mark 9 formed in a principle of recordingshown in the present embodiment may be principally lowered as comparedwith a local cavity in the recording layer 3-2 generated due to plasticdeformation or gasification (evaporation) of the surface of thetransparent substrate 2-2. As countermeasures against it, in the presentembodiment, advantageous effect that the high density and thereliability of recording information are achieved at the same time incombination with strong error correction capability (novel ECC blockstructure), as described later in “Chapter 7: Description of H Format”and “Chapter 8: Description of B Format”. Further, in the presentembodiment, PRML (Partial Response Maximum Likelihood) technique isemployed as a reproduction method, as described in the section “4-2Description of reproducing circuit in the present embodiment”, the highdensity and the reliability of recording information are achieved at thesame time in combination with an error correction technique at the timeof ML demodulation.

Among the specific characteristics of the above described presentembodiment, a description has been given with respect to the fact thatitems [α] to [γ] are the contents of technical contrivance newly devisedin the present embodiment in order to achieve “narrow track pitch” and“narrow channel bit length”. In addition, “narrow channel bit length”causes the achievement of “reduction of minimum recording mark length”.The meanings (objects) of the present embodiment relating to theremaining items [δ] and [ε ] will be described in detail. At the time ofreproduction in the H format in the present embodiment, a passage speed(line speed) of a focusing spot of light passing through the recordinglayer 3-2 is set to 6.61 m/s, and the line speed in the B format is setin the range of 5.0 m/s to 10.2 m/s.

In any case, the line speed at the time of reproduction in the presentembodiment is equal to or greater than 5 m/s. As shown in FIG. 31, astart position of a data lead-in area DTLDI in the H format is 47.6 mmin diameter. In view of the B format as well, user data is recorded inlocation equal to or greater than 45 mm in diameter. An inner peripheryof 45 mm in diameter is 0.141 m, and thus, the rotation frequency of aninformation storage medium when this position is reproduced at a linespeed of 5 m/s is obtained as 35.4 rotations/s. Video image informationsuch as TV program is provided as one of the methods utilizing awrite-once type information storing medium according to the presentembodiment. For example, when a user presses “pause (temporary stop)button” at the reproduction of the user's recorded video image, areproduction focusing spot stays on a track of its paused position. Whenthe spot stops on the track of the paused position, the user can startreproduction at the paused position immediately after a “reproductionstart button” has been pressed. For example, after the user has presseda “pause (temporary stop) button”, in the case where a customer visitsthe user's home immediately after the user has gone to toilet, there isa case in which the pause button is left to have been pressed for onehour while the user meets the customer. The write-once type informationstorage medium makes 35.4×60×60≈130,000 rotations for one hour, and thefocusing spot traces on the same track during this period (130,000repetitive playbacks). If the recording layer 3-2 is degraded due torepetitive playback and video image information cannot be reproducedafter this period, the user coming back one hour later cannot see anyportion of video image, and thus, gets angry, and in the worst case,there is a danger that the problem may be taken to court. Therefore, aminimum condition that, if the recorded video image information is notdestroyed even if such a pausing is left for one hour or longer (even ifcontinuous playback in the same track occurs), no video image data isdestroyed, requires to guarantee that at least 100,000 repetitiveplayback occurs, no reproduction degradation occurs. There is a rarecase in which a user repeats one-hour pausing (repetitive playback) 10times with respect to the same location in a general use condition.Therefore, when it is guaranteed that the write-once type informationstorage medium according to the present embodiment desirably makes1,000,000 repetitive playbacks, no problem occurs with use by thegeneral user, and it is considered sufficient to set to about 1,000,000times the upper limit value of the repetitive playback count as long asthe recording layer 3-2 is not degraded. If the upper limit value of therepetitive playback count is set to a value which significantly exceeds1,000,000 times, there occurs inconvenience that “recording sensitivityis lowered” or “medium price increases”.

In the case where the upper limit value of the above repetitivereproduction count is guaranteed, a reproduction power value becomes animportant factor. In the present embodiment, recording power is definedin a range set in formulas (8) to (13). It is said that a semiconductorlaser beam is featured in that continuous light irradiation is notstable in a value equal to or smaller than 1/80 of the maximum usepower. Because the power, which is 1/80 of the maximum use power, is inlocation in which light irradiation is just started (mode initiation isstarted), mode hopping is likely to occur. Therefore, at this lightirradiation power, the light reflected in the light reflection layer 4-2of the information storage medium comes back to a semiconductor laserlight source, there occurs a “return light noise” featured in that thelight emission amount always changes. Accordingly, in the presentembodiment, the values of the reproduction power is set below around thevalue which is 1/80 of the value described at the right side of formula(12) or formula (13):[Optical Reproduction Power]>0.19×(0.65/NA)²×(V/6.6)  (B-1)[Optical Reproduction Power]>0.19×(0.65/NA)²×(V/6.6)^(1.2)  (B-2)

In addition, the value of the optimal reproduction power is restrictedby a dynamic range of a power monitoring optical detector. Although notshown in an information recording/reproducing unit 141 of FIG. 11, arecording/reproducing optical head exists. This optical headincorporates an optical detector which monitors a light emission amountof a semiconductor laser light source. In the present embodiment, inorder to improve light irradiation precision of the reproduction powerat the time of reproduction, this optical detector detects a lightemission amount and applies a feedback to an amount of a current to besupplied to the semiconductor laser light source at the time of lightirradiation. In order to lower a price of the optical head, it isnecessary to use a very inexpensive optical detector. A commerciallyavailable, inexpensive optical detector is often molded with a resin (anoptical detecting unit is surrounded).

As disclosed in “Chapter 0: Description of Relationship between UseWavelength and the Present Embodiment”, 530 nm or less (in particular,455 nm or less) is used as a light source wavelength in the presentembodiment. In the case of this wavelength area, a resin with which theoptical detecting unit is molded (mainly, epoxy resin) causes such adegradation that occurs when ultraviolet ray has been irradiated if thewavelength light is irradiated (such as dark yellow discoloring oroccurrence of cracks (fine white stripes)) and the optical detectioncharacteristics are impaired. In particular, in the case of thewrite-once type information storage medium shown in the presentembodiment, a mold resin degradation is likely to occur because thestorage medium has a pre-groove area 11 as shown in FIGS. 8A, 8B and 8C.As a focus blurring detection system of an optical head, in order toremove adverse effect due to the diffraction light from this pre-groovearea 11, there is most often employed a “knife-edge technique” ofallocating an optical detector at an image forming position relevant tothe information storage medium (image forming magnification M is inorder of 3 times to 10 times). When the optical detector is arranged atthe image forming position, high optical density is irradiated onto amold resin because light beams are focused on the optical detector, andresin degradation due to this light irradiation is likely to occur. Thismold resin characteristic degradation mainly occurs due to a photon mode(optical action), and however, it is possible to predict an upper limitvalue of an allowable irradiation amount in comparison with a lightemission amount in a thermal mode (thermal excitation). Assuming theworst case, let us assume an optical system in which an optical detectoris arranged at an image forming position as an optical head.

From the contents described in “(1) Condition for thickness Dg ofrecording layer 3-2” in “3-2-A] Range requiring application of techniqueaccording to the present embodiment”, when an optimal characteristicchange (thermal mode) occurs in the recording layer 3-2 at the time ofrecording in the present embodiment, it is considered that a temperaturetemporarily rises in the range of 80° C. to 150° C. in the recordinglayer 3-2. In view of a room temperature of about 15° C., a temperaturedifference ΔT_(write) ranges from 65° C. to 135° C. Pulse lightemissions occur at the time of recording, and continuous light emissionsoccur at the time of reproduction. At the time of reproduction, thetemperature rises in the recording layer 3-2 and a temperaturedifference ΔT_(read) occurs. When an image forming magnification of adetecting system in the optical head is M, the optical density of thedetected light focused on the optical detector is obtained as 1/M² ofthe optical density of convergence light irradiated on the recordinglayer 3-2, and thus, a temperature rise amount on the optical detectorat the time of reproduction is obtained as ΔT_(read)/M² which is a roughestimate. In view of the fact that an upper limit value of opticaldensity, which can be irradiated on the optical detector, is convertedby the temperature rise amount, it is considered that the upper limitvalue is in order of ΔT_(read)/M²≦1° C. The image foaming magnificationof the detecting system in the optical head M is in order of 3 times to10 times in general, if the magnification M²≈10 is tentativelyestimated, it is necessary to set reproduction power so as to obtain:ΔT _(read) /ΔT _(write)≦20  (B-3)

Assuming that a duty ratio of recording pulses at the time of recordingis estimated as 50%, the following is required:[Optimal Reproduction Power]≦[Optimal recording power]/10  (B-4)

Therefore, in view of formulas (8) to (13) described later and the aboveformula (B-4), optimal reproduction power is assigned as follows:[Optimal Reproduction Power]<3×(0.65/NA)²×(V/6.6)  (B-5)[Optimal Reproduction Power]<3×(0.65/NA)²×(V/6.6)^(1/2)  (B-6)[Optimal Reproduction Power]<2×(0.65/NA)²×(V/6.6)  (B-7)[Optimal Reproduction Power]<2×(0.65/NA)²×(V/6.6)^(1/2)  (B-8)[Optimal Reproduction Power]<1.5×(0.65/NA)²×(V/6.6)  (B-9)[Optimal reproduction power]<1.5×(0.65/NA)²×(V/6.6)^(1/2)  (B-10)

(Refer to “3-2-E] Basic characteristics relating to thicknessdistribution of recording layer in the present embodiment for definitionof parameters”.) For example, when NA=0.65 and V=6.6 m/s, the followingis obtained:[Optimal reproduction power]<3 mW,[Optimal reproduction power]<2 mW, or[Optimal reproduction power]<1.5 mW.

In reality, the optical detector is fixed as compared with the fact theinformation storage medium rotates and relatively moves, and thus, inconsideration of this fact, it is necessary to further set the optimalreproduction power to be in order of ⅓ or less of the value obtained inthe above formula. In the information recording/reproducing apparatusaccording to the present embodiment, a value of the reproduction poweris set to 0.4 mW.

3-2-C] Ideal recording film structure in which a principle of recordingshown in the present embodiment is easily generated

A description will be given with respect to a method for “setting anenvironment” (recording film structure or shape) in which the aboveprinciple of recording is easily generated in the present embodiment.

As an environment in which an optical characteristic change inside ofthe above described recording layer 3-2 is likely to occur, the presentembodiment is featured in that a technical contrivance is carried out inrecording film structure or shape such as:

“in an area for forming the recording mark 9, a critical temperature atwhich an optical characteristic change is likely to occur is exceeded,and at a center part of the recording mark 9, a gasification(evaporation) temperature is not exceeded, and a surface of atransparent substrate 2-2 in the vicinity of the center part of therecording mark 9 does not exceed a thermal temperature”.

The specific contents relating to the above description will bedescribed with reference to FIGS. 7A, 7B and 7C. In FIGS. 7A, 7B and 7C,the open (blank) arrow indicates an optical path of an irradiation laserlight beam 7, and the arrow of the dashed line indicates a thermal flow.A recording film structure shown in FIG. 7A indicates an environment inwhich an optical characteristic change inside of a recording layer 3-2corresponding to the present embodiment is most likely to occur. Thatis, in FIG. 7A, the recording layer 3-2 consisting of an organic dyerecording material has uniform thickness anywhere in the range shown informula (3) or formula (4) (where the thickness is sufficiently large),and receives irradiation of the laser light beam 7 in a directionvertical to the recording layer 3-2. As described in detail in “6-1)light reflection layer (material and thickness)”, a silver alloy is usedas a material for a light reflection layer 4-2 in the presentembodiment. A material including a metal with high light reflectionfactor, in general, has high thermal conductivity and heat radiationcharacteristics without being limited to the silver alloy. Therefore,although a temperature of the recording layer 3-2 is risen by absorbingthe energy of the irradiated laser light beam 7, a heat is radiatedtoward the light reflection layer 4-2 having heat radiationcharacteristics. Although a recording film shown in FIG. 7A is formedanywhere in a uniform shape, a comparatively uniform temperature riseoccurs inside of the recording layer 3-2, and a temperature differenceat points α, β, and γ at the center part is comparatively small.Therefore, when the recording mark 9 is formed, when a criticaltemperature at which an optical characteristic change at the points αand β occurs is exceeded, a gasification (evaporation) temperature isnot exceeded at the point α of the center part; and a surface of atransparent substrate (not shown) which exists at a position which isthe closest to the point α of the center part does not exceed a thermaldeformation temperature.

In comparison, as shown in FIG. 7B, a step is provided partly of therecording film 3-2. At the points δ and ε, the radiation of the laserlight beam 7 is subjected in a direction oblique to a direction in whichthe recording layer 3-2 is arrayed, and thus, an irradiation amount ofthe laser light beam 7 per a unit area is relatively lowered as comparedwith the point α of the center part. As a result, a temperature riseamount in the recording layer 3-2 at the points δ and ε is lowered. Atthe points δ and ε as well, thermal radiation toward the lightreflection layer 4-2 occurs, and thus, the arrival temperature at thepoints δ and ε is sufficiently lowered as compared with the point α ofthe center part. Therefore, a heat flows from the point β to the point αand a heat flows from the point α to the point β, and thus, atemperature difference at the points β and γ relevant to the point α ofthe center part becomes very small. At the time of recording, atemperature rise amount at the points β and γ is low, and a criticaltemperature at which an optical characteristic change occurs is hardlyexceeded at the points β and α. As countermeasures against it, in orderto produce an optical characteristic change occurs at the points β and γ(in order to produce a critical temperature or more), it is necessary toincrease an exposure amount (recording power) of the laser light beam 7.In the recording film structure shown in FIG. 7B, a temperaturedifference at the point α of the center part relevant to the points βand γ is very large. Thus, when a current temperature has risen at atemperature at which an optical characteristic change occurs at thepoints β and γ, a gasification (evaporation) temperature is exceeded atthe point α of the center part or the surface of a transparent substrate(not shown) in the vicinity of the point α of the center part hardlyexceeds a thermal deformation temperature.

In addition, even if the surface of the recording layer 3-2 at the sideat which irradiation of the laser light beam 7 is subjected is verticalto the irradiation direction of the laser light beam 7 anywhere, in thecase where the thickness of the recording layer 3-2 changes depending ona location, there is provided a structure in which an opticalcharacteristic change inside of the recording layer 3-2 according to thepresent embodiment hardly occurs. For example, as shown in FIG. 7C, letus consider a case in which the thickness D1 of a peripheral part issignificantly small with respect to the thickness Dg of the recordinglayer 3-2 at the point α of the center part (for example, formula (2) orformula (4) is not satisfied). Even at the point α of the center part,although heat radiation toward the light reflection layer 4-2 occurs,the thickness Dg of the recording layer 3-2 is sufficiently large, thusmaking it possible to achieve heat accumulation and to achieve a hightemperature. In comparison, at the points ξ and η at which the thicknessD1 is significantly small, a heat is radiated toward the lightreflection layer 4-2 without carrying out heat accumulation, and thus, atemperature rise amount is small. As a result, heat radiation towardpoints β, δ, and ξ in order and heat radiation toward points γ, ε, and ηin order occurs as well as heat radiation toward the light reflectionlayer 4-2, and thus, as in FIG. 7B, a temperature difference at thepoint α of the center part relevant to points β and γ becomes verylarge. When an exposure amount of the laser light beam 7 (recordingpower) is increased in order to produce an optical characteristic changeat the points β and γ (in order to produce a critical temperature ormore), the gasification (evaporation) temperature at the point α of thecenter part is exceeded or the surface of the transparent substrate (notshown) in the vicinity of the point α of the center part easily exceedsa thermal deformation temperature.

Based on the contents described above, referring to FIGS. 8A, 8B and 8C,a description will be given with respect to: the contents of a technicalcontrivance in the present embodiment relating to the pre-grooveshape/dimensions for providing “setting of environment (structure orshape of a recording film)” in which a principle of recording accordingto the present embodiment is likely to occur; and the contents of atechnical contrivance in the present embodiment relating to a thicknessdistribution of the recording layer. FIG. 8A shows a recording filmstructure in a conventional write-once type information storage mediumsuch as CD-R or DVD-R; and FIGS. 8B and 8C each show a recording filmstructure in the present embodiment. In the invention, as shown in FIGS.8A, 8B and 8C, a recording mark 9 is formed in a pre-groove area 11.

3-2-D] Basic characteristics relating to pre-groove shape/dimensions inthe present embodiment

As shown in FIG. 8A, there have been many cases in which a pre-groovearea 11 is formed in a “V-groove” shape in a conventional write-oncetype information storage medium such as CD-R or DVD-R. In the case ofthis structure, as described in FIG. 7B, the energy absorptionefficiency of the laser light beam 7 is low, and the temperaturedistribution non-uniformity in the recording layer 3-2 becomes verylarge. The present embodiment is featured in that, in order to makeclose to an ideal state of FIG. 7A, a planar shape orthogonal to atraveling direction of the incident laser light beam 7 is provided inthe pre-groove area 11 at the side of at least the “transparentsubstrate 2-2”. As described with reference to FIG. 7A, it is desirablethat this planar area be as wide as possible. Therefore, the presentembodiment is secondarily featured in that the planar area is providedin the pre-groove area 11 and the width Wg of the pre-groove area 11 iswider than the width W1 of a land area (Wg>W1). In this description, thewidth Wg of the pre-groove area and the width W1 of the land area aredefined as their respective widths at a position at which there crossesa plane having an intermediate height between a height at a planarposition of the pre-groove area and a height at a position at which theland area becomes the highest and an oblique surface in the pre-groove.

A discussion has been made using thermal analysis, data has beenrecorded in a write-once type information storage medium actuallyproduced as a prototype, substrate deformation observation due to asectional SEM (scanning type electronic microscope) image at theposition of the recording mark 9 has been made, and observation of thepresence or absence of a cavity generated due to gasification(evaporation) in the recording layer 3-2 has been repeated. As a result,it is found that advantageous effect is attained by widening the widthWg of the pre-groove area more significantly than the width W1 of theland area. Further, a ratio of the pre-groove area width Wg and the landarea width W1 is Wg:W1=6:4, and desirably, is greater than Wg:W1=7:3,whereby it is considered that a local optical characteristic change inthe recording layer 3-2 is likely to occur while the change is morestable at the time of recording. As described above, when a differencebetween the pre-groove area width Wg and the land area width W1 isincreased, a flat surface is eliminated from the top of the land area12, as shown in FIG. 8C. In the conventional DVD-R disk, a pre-pit (landpre-pit: not shown) is formed in the land area 12, and a format forrecording address information or the like in advance is realized here.Therefore, it is conditionally mandatory to form a flat area in the landarea 12. As a result, there has been a case in which the pre-groove area11 is formed in the “V-groove” shape. In addition, in the conventionalCD-R disk, a wobble signal has been recorded in the pre-groove area 11by means of frequency modulation. In a frequency modulation system inthe conventional CD-R disk, slot gaps (a detailed description of eachformat is given in detail) are not constant, and phase adjustment at thetime of wobble signal detection (PLL: synchronization of PLL (Phase LockLoop)) has been comparatively difficult. Thus, a wall face of thepre-groove area 11 is concentrated (made close to the V-groove) in thevicinity of a center at which the intensity of a reproducing focusingspot is the highest and a wobble amplitude amount is increased, wherebythe wobble signal detection precision has been guaranteed. As shown inFIGS. 8B and 8C, after the flat area in the pre-groove area 11 in thepresent embodiment has been widened, when the oblique surface of thepre-groove area 11 is shifted to the outside relatively than a centerposition of the reproducing focusing spot, a wobble detection signal ishardly obtained. The present embodiment is featured in that the width Wgof the pre-groove area described above is widened and the H formatutilizing PSK (Phase Shift Keying) in which slot gaps at wobbledetection is always fixedly maintained or the B format utilizing FSK(Frequency Shift Keying) or STW (Saw Tooth Wobble) are combined, wherebystable recording characteristics are guaranteed (suitable to high speedrecording or layering) at low recording power and stable wobble signaldetection characteristics are guaranteed. In particular, in the Hformat, in addition to the above combination, “a ratio of a wobblemodulation is lowered more significantly than that of a non-modulationarea”, thereby facilitating synchronization at the time of wobble signaldetection more significantly, and further, stabilizing wobble signaldetection characteristics more significantly.

3-2-E] Basic characteristics relating to thickness distribution ofrecording layer 3-2 in the present embodiment

In the present description, as shown in FIGS. 8B and 8C, the thicknessin a portion at which the recording layer 3-2 in the land area 12 is thethickest is defined as recording layer thickness D1 in the land area 12;and a portion at which the recording layer 3-2 in the pre-groove area 11is the thickest is defined as recording layer thickness Dg in thepre-groove area. As has been described with reference to FIG. 7C, therecording layer thickness D1 in the land area is relatively increased,whereby a local optical characteristic change in the recording layer isstably likely to occur at the time of recording.

In the same manner as that described above, a discussion has been madeusing thermal analysis, data has been recorded in a write-once typeinformation storage medium actually produced as a prototype, substratedeformation observation and observation of the presence or absence of acavity generated due to gasification (evaporation) in the recordinglayer 3-2 by a sectional SEM (scanning type electronic microscope) imageat the position of the recording mark 9 have been made. As a result, ithas been found necessary to set a ratio between the recording layerthickness Dg in the pre-groove area and the recording layer thickness D1in the land area to be equal to or smaller than Dg:D1=4:1. Further,Dg:D1=3:1 is set, and desirably, Dg:D1=2:1 is set, thereby making itpossible to guarantee stability of a principle of recording in thepresent embodiment.

3-3) Recording characteristics common to organic dye recording film inthe present embodiment

As one of “3-2-B] basic characteristics common to an organic dyerecording material in the present embodiment”, the present embodiment isfeatured by recording power control, as described in item [γ].

The formation of the recording mark 9 due to a local opticalcharacteristic change in the recording layer 3-2 occurs at atemperature, which is much lower than a plastic deformation temperatureof the conventional transparent substrate 2-2, at a thermaldecomposition temperature in the recording layer 3-2, or a gasification(evaporation) temperature. Thus, an upper limit value of recording poweris restricted so as not ensure that the transparent substrate 2-2locally exceeds a plastic deformation temperature at the time ofrecording or a thermal decomposition temperature or a gasification(evaporation) temperature is locally exceeded in the recording layer3-2.

In parallel to discussion using thermal analysis, by using an apparatusdescribed later in “4-1) Description of structure and characteristics ofreproducing apparatus or recording/reproducing apparatus in the presentembodiment” and by using a recording condition described later in “4-3)Description of recording condition in the present embodiment”, there hasbeen made a demonstration of a value of optimal power in the case whererecording has been carried out in a principle of recording shown in thepresent embodiment. A numerical aperture (NA) value of an objective lensin the recording/reproducing apparatus used in a demonstration test hasbeen 0.65, and a line speed at the time of recording has been 6.61 m/s.As a value of recording power (Peak Power) defined later in “4-3)Description of recording condition in the present embodiment”, it hasbeen found that:

Gasification (evaporation) occurs with most of an organic dye recordingmaterial at 30 mW, and a cavity occurs in a recording mark;

A temperature of the transparent substrate 2-2 at a position in thevicinity of the recording layer 3-2 significantly exceeds a glasstransition temperature;

A temperature of the transparent substrate 2-2 at a position in thevicinity of the recording layer 3-2 reaches a plastic deformationtemperature (glass transition temperature) at 20 mW;

15 mW or less is desirable in consideration of a margin such as surfacepre-warping or recording power change of an information storage medium.

The “recording power” described above denotes a sum of exposure amountirradiated to the recording layer 3-2. The optical energy density at acenter part of a focusing spot and at a portion at which the opticalintensity density is the highest is obtained as parameters targeted fordiscussion in the present embodiment. The focusing spot size isinversely proportional to the NA value, and thus, the optical energydensity at the center part of the focusing spot increases in proportionto a square of the NA value. Therefore, the current value can beconverted to a value of optimal recording power in the B formatdescribed later or another format (another NA value) shown in FIG. 1(D3) by using a relational formula below:[Recording power applicable to different NA values]=[Recording powerwhen NA=0.65]×0.65² /NA ²  (5)

Further, optimal recording power changes depending on a line speed V inphase change type recording material. In general, it is said thatoptimal recording power changes in proportion to a ½ square of a linespeed V in phase change type recording material, and changes inproportion to a line speed V in organic dye recording material.Therefore, a conversion formula of optimal recording power considering aline speed V, obtained by extending formula (5), is obtained as follows:[General recording power]=[Recording power when NA=0.65; 6.6m/s]×(0.65/NA)²×(V/6.6)  (6)or[General recording power]=[Recording power when NA=0.65; 6.6m/s]×(0.65/NA)²×(V/6.6)^(1/2)  (7)

When the above discussion result is summarized, as recording power forguaranteeing a principle of recording shown in the present embodiment,it is desirable to set an upper limit value such as:[Optimal recording power]<30×(0.65/NA)²×(V/6.6)  (8)[Optimal recording power]<30×(0.65/NA)²×(V/6.6)^(1/2)  (9)[Optimal recording power]<20×(0.65/NA)²×(V/6.6)  (10)[Optimal recording power]<20×(0.65/NA)²×(V/6.6)^(1/2)  (11)[Optimal recording power]<15×(0.65/NA)²×(V/6.6)  (12)[Optimal recording power]<15×(0.65/NA)²×(V/6.6)^(1/2)  (13)

From among the above formulas, a condition for formula (8) or formula(9) is obtained as a mandatory condition; a target condition for formula(10) or formula (11) is obtained; and a condition for formula (12) orformula (13) is obtained as a desirable condition.

3-4) Description of characteristics relating to “H-L” recording film inthe present embodiment

A recording film having characteristics that a light reflection amountin a recording mark 9 is lower than that in an unrecorded area isreferred to as an “H-L” recording film. In contrast, a recording film inwhich the above light reflection amount is high is referred to as an“L-H” recording film. Among them, with respect to the “H-L” recordingfilm, the present embodiment is featured in that:

1) an upper limit value is provided at a ratio of absorbance at areproduction wavelength relevant to absorbance at a λ_(max write)position of light absorption spectra; and

2) a light absorption spectra profile is changed to form a recordingmark.

A detailed description relating to the above contents will be given withreference to FIGS. 9 and 10. In the “H-L” recording film in the presentembodiment, as shown in FIG. 9, a wavelength of λ_(max write) is shorterthan a use wavelength utilized for recording/reproduction (in thevicinity of 405 nm). As is evident from FIG. 10, in the vicinity of awavelength of λ_(max write), a change of absorbance is small between anunrecorded portion and a recorded portion. If a change of absorbance issmall between the unrecorded portion and the recorded portion, a largereproduction signal amplitude cannot be obtained. Even if a wavelengthchange of a recording or reproducing laser light source occurs, in viewof the fact that recording or reproduction can be stably carried out, inthe present embodiment, as shown in FIG. 9, a design of the recordingfilm 3-2 is made so that a wavelength of λ_(max write) arrives at theoutside ranging from 355 nm to 455 nm, i.e., arrives at the shorterwavelength side than 355 nm.

The relative absorbance at 355 nm, 455 nm, and 405 nm described in“Chapter 0: Description of Relationship between Use Wavelength and thePresent Embodiment” when the absorbance at a position of λ_(max write)defined in “2-1) Difference in principle of recording/recording filmstructure and difference in basic concept relating to reproductionsignal generation”, is defined as Ah₃₅₅, Ah₄₅₅, and Ah₄₀₅.

In the case where of Ah₄₀₅=0.0, the light reflection factor from arecording film in an unrecorded state coincides with that at 405 nm inthe light reflection layer 4-2. A light reflection factor of the lightreflection layer 4-2 will be described later in detail in the section“6-1) Light reflection layer”. Hereinafter, a description will be givenwith respect to the fact that the light reflection factor of the lightreflection layer 4-2 is defined as 100% for the sake of simplification.

In the write-once type information storage medium using an “H-L”recording film in the present embodiment, a reproduction circuit is usedin common to a case of using a read-only type information storage medium(HD DVD-ROM disk) in the case of a one-sided single layer film.Therefore, in this case, an optical reflection factor is defined as 45%to 85% in accordance with a light reflection factor of the reflectiononly information storage medium (HD DVD-ROM disk) of a one-sided singlelayer film. Therefore, it is necessary to set the light reflectionfactor at an unrecorded position to 40% or more. Because 1−0.4=0.6, itis possible to intuitively understand whether or not the absorbanceAh₄₀₅ at 405 nm may be set:Ah ₄₀₅≦0.6  (14)

In the case where formula (14) above is met, it is possible to easilyunderstand that the light reflection factor can be set to 40% or more.Thus, in the present embodiment, an organic dye recording material,which meets formula (14) in an unrecorded location, is selected. Theabove formula (14) assumes that, in FIG. 9, the light reflection factoris obtained as 0% when the light reflection layer 4-2 is reflected overthe recording layer 3-2 with a light beam having a wavelength ofλ_(max write). However, in reality, at this time, the light reflectionfactor is not obtained as 0%, and has a certain degree of lightreflection factor. Thus, strictly, there is a need for correctionrelevant to formula (14). In FIG. 9, if the light reflection factor isdefined as Rλ_(max write) when the light reflection layer 4-2 has beenreflected over the recording layer 3-2 with a light beam having awavelength of λ_(max write), a strict conditional formula in which thelight reflection factor at an unrecorded position is set to 40% or moreis obtained as follows:I−Ah ₄₀₅×(1−Rλ _(max write))≧0.4  (15)

In the “H-L” recording layer, in many cases, Rλ_(max write))≧0.25, andthus, formula (15) is established as follows:Ah ₄₀₅≦0.8  (16)

In the “H-L” recording film according to the present embodiment, it isconditionally mandatory to meet formula (16). Characteristics of theabove formula (14) has been provided, and further, a detailed opticalfilm design has been made under a condition that the film thickness ofthe recording layer 3-2 meets the condition for formula (3) or formula(4), in consideration of a variety of margins such as a film thicknesschange or a wavelength change of reproduction light. As a result, it hasbeen found desirable that:Ah ₄₀₅≦0.3  (17)

Assuming that formula (14) is established, when:Ah ₄₅₅≦0.6  (18)orAh ₃₅₅≦0.6  (19),

the recording/reproducing characteristics are more stable. This isbecause, in the case where formula (14) meets any of at least formulas(18) and (19) when formula (14) is established, the value of Ah becomes0.6 or less in the range of 355 nm to 405 nm or in the range of 405 nmto 455 nm (occasionally in the range of 355 nm to 455 nm), and thus,even if a fluctuation occurs at a light emission wavelength of arecording laser light source (or a reproducing laser light source), avalue of absorbance does not change drastically.

As a specific principle of recording of the “H-L” recording film in thepresent embodiment, there is utilized a phenomenon of “array changebetween molecules” or “molecular structure change in molecule” in arecording mechanism listed in item [α] in “3-2-B] Basic featured commonto organic dye recording material in the present embodiment” which hasbeen described as a specific principle of recording of the “H-L”recording film in the present embodiment. As a result, as described inthe above item (2), a light absorption spectrum profile is changed. Thelight absorption spectrum profile in a recording mark in the presentembodiment is indicated by the solid line shown in FIG. 10, and thelight absorption spectrum profile in an unrecorded location issuperimposed by the dashed line, thereby making it possible to comparethese profiles with each other. In the present embodiment, the lightabsorption spectrum profile in the recording mark changes comparativelybroadly, and there is a possibility that a molecular structure change inmolecules occurs and partial precipitation (coal tar) of carbon atomsoccurs. The present embodiment is featured in that a value of awavelength λ1 _(max) at which the absorbance in the recording markbecomes maximal is made closer to a reproduction wavelength of 405 nmthan a value of a wavelength λ_(max write) at an unrecorded position,thereby generating a reproduction signal in the “H-L” recording film. Inthis manner, the absorbance at the wavelength λ1 _(max) at which theabsorbance is the highest becomes smaller than “1”, and a value of theabsorbance Al₄₀₅ at a reproduction wavelength of 405 nm becomes greaterthan a value of Ah₄₀₅. As a result, a total light reflection factor in arecording mark is lowered.

In the H format in the present embodiment, as a modulation system, thereis employed ETM (Eight to Twelve: 8-bit data code is converted to12-channel bit) and RLL (1, 10) (Among a code train after modulated, aminimum inversion length relevant to a 12-channel bit length T is 2 T,and a maximum inversion length is 11 T). Where performance evaluation ofa reproduction circuit described later in “4-2) Description ofreproducing circuit in the present embodiment) is carried out, in orderto stably carry out reproduction by the reproducing circuit, it has beenfound necessary to meet that a ratio of [a differential valueI11=I_(11H)−I_(11L), where I_(11H) is a reproduction signal amount froman unrecorded area having a sufficiently long length (11 T) and I_(11L)is a reproduction signal amount from a recording mark having thesufficiently long length (11 T) to [I_(11H)] is:I ₁₁ /I _(11H)≧0.4  (20) or preferably,I ₁₁ /I _(11H)>0.2  (21)

In the present embodiment, a PRML method is utilized at the time ofsignal reproduction recorded at high density, and a signal processorcircuit and a state transition chart shown in FIGS. 15 to 17 is used (Adetailed description is given later). In order to precisely carry outdetection in accordance with a PRML technique, the linearity of areproduction signal is requested. The characteristic of the signalprocessor circuit shown in FIGS. 15 and 16 has been analyzed based onthe state transition chart shown in FIG. 17, in order to ensure thelinearity of the above reproduction signal. As a result, it has beenfound necessary to meet that a ratio relevant to the above I₁₁ of avalue when a recording mark having a length of 3 T and a reproductionsignal amplitude from a repetition signal of an unrecorded space isdefined as I₃ meets:I ₃ /I ₁₁≧0.35  (22); or desirably,I ₃ /I ₁₁>0.2  (23)

In view of a condition for the above formula (16), the presentembodiment is technically featured in that a value of Al₄₀₅ has been setso as to meet formulas (20) and (21). Referring to formula (16), thefollowing is obtained:1−0.3=0.7  (24)

In view of formula (24), from a correlation with formula (20), thefollowing condition is derived:(Al ₄₀₅−0.3)/0.7≧0.4, that is,Al₄₀₅≧0.58  (25)

Formula (25) is a formula derived from a very coarse result ofdiscussion, and is merely shown as a basic concept. Because the Ah₄₀₅setting range is specified in accordance with formula (16), in thepresent embodiment, at least a condition for Al₄₀₅ is mandatory as:Al ₄₀₅>0.3  (26)

As a method for selecting an organic dye material suitable to a specific“H-L” recording layer, there is selected an organic dye material forwhich, in the present embodiment, based on an optical film design, arefractive factor range in an unrecorded state is n₃₂=1.3 to 2.0; theabsorption coefficient range is k₃₂=0.1 to 0.2, desirably n₃₂=1.7 to1.9; the absorption coefficient range is k₃₂=0.15 to 0.17, and a seriesof conditions described above are met.

In the “H-L” recording film shown in FIG. 9 or 10, in light absorptionspectra in an unrecorded area, although a wavelength of λ_(max write) isshorter than a wavelength of reproduction light or recording/reproducinglight (for example, 405 nm), the wavelength of λ_(max write) may belonger than a wavelength of reproduction light or recording/reproducinglight (for example, 405 nm), without being limited thereto.

In odder to meet the above formula (22) or formula (23), the thicknessDg of the recording layer 3-2 is influenced. For example, if thethickness Dg of the recording layer 3-2 significantly exceeds anallowable value, optical characteristics of only a part coming intocontact with the transparent substrate 2-2 in the recording layer 3-2are changed as a state that follows forming of the recording mark 9,whereby the optical characteristics of a portion coming into contactwith the light reflection layer 4-2 adjacent to its location areobtained as a value equal to that in the unrecorded area. As a result, areproduction light amount change is lowered, and a value of I₃ informula (22) or formula (23) is reduced, and a condition for formula(22) or formula (23) cannot be met. Therefore, in order to meet formula(22), as shown in FIGS. 8B and 8C, it is necessary to make a change tothe optical characteristics of a portion which comes into contact withthe light reflection layer 4-2 in the recording mark 9. Further, if thethickness Dg of the recording layer 3-2 significantly exceeds anallowable value, a temperature gradient occurs in the thicknessdirection in the recording layer 3-2 when the recording mark is formed.Then, before reaching the optical characteristic change temperature at aportion coming into contact with the light reflection layer 4-2 in therecording layer 3-2, a gasification (evaporation) temperature of aportion coming into contact with the transparent substrate 2-2 isexceeded or a thermal deformation temperature is exceeded in thetransparent substrate 2-2. For the above reason, in the presentembodiment, in order to meet formula (22), the thickness Dg of therecording layer 3-2 is set to “3 T” or less based on the discussion ofthermal analysis; and a condition meeting formula (23) is such that thethickness Dg of the recording layer 3-2 is set to “3×3 T” or less.Basically, in the case where the thickness Dg of the recording layer 3-2is equal to or smaller than “3 T”, although formula (22) can be met, thethickness may be set to “T” or less in consideration of effect of a tiltdue to a facial motion or warping of the write-once type informationstorage medium or a margin relevant to a focal blurring. Inconsideration of a result obtained by formulas (1) and (2) describedpreviously, the thickness Dg of the recording layer 3-2 in the presentembodiment is set in the range assigned in a required minimum conditionthat:9 T≧Dg≧λ/8n ₃₂  (27)

and in a desired condition that:3 T≧Dg≧λ/4n ₃₂  (28)

Without being limited thereto, the severest condition can be defined as:T≧Dg≧λ/4n ₃₂  (29)

As described later, a value of the channel bit length T is 102 nm in theH format, and is 69 nm to 80 nm in the B format. Thus, a value of 3 T is306 nm in the H format and is 207 nm to 240 nm in the B format. A valueof 9 T is 918 nm in the H format and is 621 nm to 720 nm in the Bformat. Here, although an “H-L” recording film has been described, theconditions for formulas (27) to (29) can be applied to an “L-H”recording film without being limited thereto.

Chapter 4 Description of Reproducing Apparatus or Recording/ReproducingApparatus and Recording Condition/Reproducing Circuit

4-1) Description of structure and characteristics of reproducingapparatus or recording/reproducing apparatus in the present embodiment

FIG. 11 shows an illustration of a structure in an embodiment of aninformation recording/reproducing apparatus. In FIG. 11, an upper sideof a control unit 143 mainly indicates an information recording controlsystem for an information storage medium. In the embodiment of theinformation reproducing apparatus, a structure excluding the informationrecording control system in FIG. 11 corresponds to the above structure.In FIG. 11, the arrow drawn by the thick solid line indicates a flow ofmain information which designates a reproduction signal or a recordingsignal; the arrow of the thin solid line denotes a flow of information;the arrow of the one-dotted chain line denotes a reference clock line;and the arrow of the thin dashed line denotes a command indicatingdirection.

An optical head (not shown) is arranged in an informationrecording/reproducing unit 141 shown in FIG. 11. In the presentembodiment, although a wavelength of a light source (semiconductorlaser) used in the optical head is 405 nm, the present embodiment is notlimited thereto, and there can be used a light source having a usewavelength equal to or shorter than 620 nm or 530 nm or a light sourceranging from 355 nm to 455 nm, as described previously. In addition, twoobjective lenses used to focus the light beam having the abovewavelength onto the information storage medium may be incorporated inthe optical head. In the case where a recording/reproducing operation iscarried out with respect to an information storage medium in the Hformat, an objective lens having a NA value of 0.65 is used. A structureis provided such that, in the case where a recording/reproducingoperation is carried out with respect to an information storage mediumin the B format, an objective lens having NA=0.85 is used. As anintensity distribution of incident light immediately before the light isincident to an objective lens, the relative intensity at the peripheryof the objective lens (at the boundary position of an aperture) when thecenter intensity is set to “1” is referred to as “RIM Intensity”. Avalue of the RIM intensity in the H format is set in the range of 55% to70%. At this time, a wave surface aberration amount in the optical headis optically designed so as to be 0.33λ (0.33λ or less) with respect toa use wavelength λ.

In the present embodiment, a partial response maximum likelihood (PRML)is used for information reproduction to achieve high density of aninformation storage medium (FIG. 1, point [A]). As a result of a varietyof tests, when PR(1, 2, 2, 2, 1) is used as a PR class to be used, linedensity can be increased and the reliability of a reproduction signalcan be improved (i.e., demodulation reliability can be improved) when aservo correction error such as a focal blurring or a track shift hasoccurred. Thus, in the present embodiment, PR(1, 2, 2, 2, 1) is employed(FIG. 1, point [A1]). In the present embodiment, a channel bit patternafter modulated is recorded in an information storage medium inaccordance with a (d, k; m, n) modulation rule (In the above describedmethod, this denotes RLL(d, k) of m/n modulation). Specifically, ETM(Eight to Twelve Modulation) for converting 8-bit data to a 12-channelbit (m=8, n=12) is employed as a modulation system, and a condition ofRLL (1, 10) in which a minimum value having continuous “0”s is definedas d=1, and a maximum value is defined as k=10 as a run length limitedRLL restriction for apply limitation to a length that follows “0” in thechannel bit pattern after modulated must be met. In the presentembodiment, in order to achieve high density of an information storagemedium, a channel bit gap is reduced to the minimum. As a result, forexample, after a pattern “101010101010101010101010” which is arepetition of a pattern of d=1 has been recorded in the informationstorage medium, in the case where the data is reproduced in aninformation recording/reproducing unit 141, the data is close to ashutdown frequency having MTF characteristics of a reproducing opticalsystem, and thus, a signal amplitude of a reproduced raw signal isformed in a shape almost hidden by noise. Therefore, a partial responsemaximum likelihood (PRML) technique is used as a method for thusreproducing a recording mark or a pit, which has been dense up to thevicinity of a limit of the MTF characteristics (shutdown frequency).That is, a signal reproduced from the information recording/reproducingunit 141 receives reproducing waveform correction by a PR equalizercircuit 130. A signal having passed through the PR equalizer circuit 130is sampled by converting a signal after passing through the PR equalizercircuit 130 to a digital amount in accordance with a timing of areference clock 198 sent from a reference clock generating circuit 160;the sampled signal is converted to a digital data by an AD converter169; and a Viterbi decoding process is carried out in a Viterbi decoder156. The data after Viterbi-decoded is processed as data, which iscompletely similar to binary data at a conventional slice level. In thecase where the PRML technique has been employed, if a sampling timingobtained by the AD converter 169 is shifted, an error rate of the dataafter Viterbi decoded increases. Therefore, in order to enhanceprecision of the sampling timing, the information reproducing apparatusor information recording/reproducing apparatus according to the presentembodiment has another sampling timing sampling circuit in particular(combination of Schmidt trigger binarizing circuit 155 and PLL circuit174). This Schmidt trigger circuit 155 has a specific value (forwarddirection voltage value of diode in actuality) at a slice referencelevel for binarizing, and is featured in that binarizing is provide onlywhen the specific width has been exceeded. Therefore, for example, asdescribed above, in the case where a pattern of“101010101010101010101010” has been input, a signal amplitude is verysmall, and thus, switching of binarizing does not occur. In the casewhere “1001001001001001001001” or the like, for example, being a patternof a rarer fraction than the above, has been input, an amplitude of areproducing raw signal increases, and thus, the polarity switching of abinary signal occurs in accordance with a timing of “1” by a Schmidttrigger binarizing circuit 155. In the present embodiment, an NRZI (NonReturn to Zero Invert) technique is employed, and a position of “1” ofthe above pattern coincides with an edge section (boundary section) of arecording mark or a pit.

A PLL circuit 174 detects a shift in frequency and phase between abinary signal which is an output of this Schmidt trigger binarizingcircuit 155 and a signal of a reference clock 198 sent from a referenceclock generating circuit 160 to change the frequency and phase of theoutput clock of the PLL circuit 174. A reference clock generatingcircuit 160 applies a feedback to (a frequency and a phase) of areference clock 198 so as to lower an error rate after Viterbi decoded,by using an output signal of this PLL circuit 174 and decodingcharacteristic information on a Viterbi decoder 156 and a convergencelength (information on (distance to convergence)) in a path metricmemory in the Viterbi decoder 156, although is not specifically shown).The reference clock 198 generated by this reference clock generatingcircuit 160 is utilized as a reference timing at the time ofreproduction signal processing.

A sync code position sampling unit 145 serves to detect the presence andposition of a sync code, which coexists in an output data train of theViterbi decoder 156 and to sample a start position of the above outputdata. While this start position is defined as a reference, a demodulatorcircuit 152 carries out a demodulating process with respect to datatemporarily stored in a shift resistor circuit 170. In the presentembodiment, the above temporarily stored data is returned to itsoriginal bit pattern with reference to a conversion table recorded in ademodulating conversion table recording unit 154 on 12-channel bit bybit basis. Then, an error correcting process is performed by an ECCdecoding circuit 162, and descrambling is carried out by a descramblingcircuit 159. Address information is recorded in advance by wobblemodulation in a recording type (rewritable type or write-once type)information storage medium according to the present embodiment. A wobblesignal detecting unit 135 reproduces this address information (i.e.,judges the contents of a wobble signal), and supplies informationrequired to provide an access to a desired location to the control unit143.

A description will be given with respect to an information recordingcontrol system provided at the upper side than the control unit 143.After data ID information has been generated from a data ID generatingunit 165 in accordance with a recording position on an informationstorage medium, when copy control information is generated by a CPR_MAIdata generating unit 167, a variety of information on data ID, IED,CPR_MAI, and EDC is added to information to be recorded by a data ID,IED, CPR_MAI, and EDC adding unit 168. After the added information hasbeen descrambled by the descrambling circuit 157, an ECC block is formedby an ECC encoding circuit 161, and the ECC block is converted to achannel bit pattern by a modulating circuit 151. A sync code is added bya sync code generating/adding unit 146, and data is recorded in aninformation storage medium in the information recording/reproducing unit141. At the time of modulation, DSV values after modulated aresequentially calculated by a DSV (Digital Sum Value) calculating unit148, and the serially calculated values are fed back to code conversionafter modulated.

FIG. 12 shows a detailed structure of peripheral portions including thesync code position detector unit 145 shown in FIG. 11. A sync code iscomposed of a sync position detecting code section and a variable codesection having a fixed pattern. From the channel bit pattern output froma Viterbi decoder, a sync position detecting code detector unit 182detects a position of a sync position detecting code section having theabove fixed pattern. Variable code transfer units 183 and 184 sampledata on a variable code which exists before and after the detectedposition, and judge in which sync frame in a sector the sync code ispositioned, the sync code being detected by an identifying unit 185 fordetecting a sync position having the above fixed pattern. Userinformation recorded on an information storage medium is sequentiallytransferred in order of a shift register circuit 170, a demodulationprocessing unit 188 in a demodulator circuit 152, and an ECC decodingcircuit 162.

In the present embodiment, in the H format, the high density of theinformation storage medium is achieved (in particular, line density isimproved) by using the PRML system for reproduction in a data area, adata lead-in area, and a data lead-out area. In addition, compatibilitywith a current DVD is ensured and reproduction stability is ensured byusing a slice level detecting system for reproducing in a system lead-inarea and a system lead-out area. (A detailed description will be givenlater in “Chapter 7: Description of H Format”.)

4-2) Description of reproducing circuit in the present embodiment

FIG. 13 shows an embodiment of a signal reproducing circuit using aslice level detecting system used at the time of reproduction in asystem lead-in area and a system lead-out area. A quadrature opticaldetector 302 in FIG. 13 is fixed into the optical head, which exists inthe information recording/reproducing unit 141 in FIG. 11. Hereinafter,a signal having taken a sum of detection signals obtained from opticaldetecting cells 1 a, 1 b, 1 c, and 1 d of the quadrature opticaldetector 302 is referred to as a “lead channel 1 signal”. From apreamplifier 304 to a slicer 310 in FIG. 13 corresponds to a detailedstructure in the slice level detecting circuit 132 in FIG. 11. Areproduction signal obtained from an information storage medium issubjected to a waveform equalizing process by a pre-equalizer 308 afterthe signal has passed through a high path filter 306 which shuts out afrequency component lower than a reproduction signal frequencybandwidth. According to testing, it has found that this pre-equalizer308 minimizes a circuit scale by using a 7-tap equalizer and can detecta reproduction signal precisely. Thus, in the present embodiment, the7-tap equalizer is used. A VFO circuit/PLL 312 in FIG. 13 corresponds tothe PLL circuit 174 in FIG. 11; and a demodulating/ECC decoding circuit314 in FIG. 13 corresponding to the decoding circuit 152 and the ECCdecoding circuit 162 in FIG. 11.

FIG. 14 shows a detailed structure in a circuit of the slicer 310 inFIG. 13. A binary signal after sliced is generated by using a comparator316. In response to an inverting signal of binary data after binarizedis set at a slice level at the time of binarizing. In the presentembodiment, a cutoff frequency of this low path filter is set to 5 KHz.When this cutoff frequency is high, a slice level change is fast, andthe low path filter is affected by noise. In contrast, if a cutofffrequency is low, a slice level response is slow, and thus, the filteris affected by dust or scratch on the information storage medium. Thecutoff frequency is set to 5 KHz in consideration of a relationshipbetween RLL(1, 10) and a reference frequency of a channel bit describedpreviously.

FIG. 15 shows a signal processor circuit using a PRML detectingtechnique used for signal reproduction in a data area, a data lead-inarea, and a data lead-out area. A quadrature optical detector 302 inFIG. 15 is fixed into the optical head, which exists in the informationrecording/reproducing unit 141 in FIG. 11. Hereinafter, a signal havingtaken a sum of detection signals obtained from the optical detectingcells 1 a, 1 b, 1 c, and id of the quadrature optical detector 302 isreferred to as a “lead channel 1 signal”. A derailed structure in the PRequalizer circuit 130 in FIG. 11 is composed of circuits from apreamplifier 304 to a tap controller 332, an equalizer 330, and anoffset canceller 336 in FIG. 15. A PLL circuit 334 in FIG. 15 is a partin the PR equalizer circuit 130, and denotes an element other than theSchmidt trigger binarizing circuit 155. A primary cutoff frequency of ahigh path filter circuit 306 in FIG. 15 is set at 1 KHz. A pre-equalizercircuit 308 uses a 7-tap equalizer in the same manner as that in FIG. 13(because the use of the 7-tap equalizer minimizes a circuit scale andcan detect a reproduction signal precisely). A sample clock frequency ofan A/D converter circuit 324 is set to 72 MHz, and a digital output isproduced as an eight-bit output. In the PRML detecting technique, if areproduction signal is affected by a level change (DC offset) of itsentire signal, an error is likely to occur at the time of Viterbidemodulation. In order to eliminate such an effect, there is provided astructure of correcting an offset by the offset canceller 336 using asignal obtained from an equalizer output. In the embodiment shown inFIG. 15, an adaptive equalizing process is carried out in the PRequalizer circuit 130. Thus, a tap controller for automaticallycorrecting tap coefficients in the equalizer 330 is utilized byutilizing an output signal of the Viterbi decoder 156.

FIG. 16 shows a structure in the Viterbi decoder 156 shown in FIG. 11 or15. A branch metric relevant to all branches, which can be predicted inresponse to an input signal, is calculated by a branch metriccalculating unit 340, and the calculated value is sent to an ACS 342.The ACS 342 is an acronym of Add Compare Select, which calculates a pathmetric obtained by adding branch metrics in response to each of thepasses which can be predicted in the ACS 342 and transfers thecalculation result to a path metric memory 350. At this time, in the ACS342, a calculating process is carried out with reference to theinformation contained in the path metric memory 350. A path memory 346temporarily stores a value of the path metric corresponding to each path(transition) state and such each path, which can be predicted in thememory 346, the value being calculated by the ACS 342. An output switchunit 348 compares a path metric corresponding to each path, and selectsa path when a path metric value becomes minimal.

FIG. 17 shows a state change in PR(1, 2, 2, 2, 1) class in the presentembodiment. A change of a state which can be obtained in the PR(1, 2, 2,2, 1) class can be made as only a change shown in FIG. 17, and a pathwhich can exist (which can be predicted) at the time of decoding isidentified in the Viterbi decoder 156 based on a transition chart inFIG. 17.

4-3) Description of recording condition in the present embodiment

“A description of optimal recording power (peak power) in the presentembodiment has been given in “3-3) Recording characteristics common toorganic dye recording film in the present embodiment”. Referring to FIG.18, a description will be given with respect to a recording waveform(exposure condition at the time of recording) used when the optimalrecording power is checked.

The exposure levels at the time of recording have four levels ofrecording power (peak power), bias power 1, bias power 2, and bias power3. When a long (4 T or more) recording mark 9 is formed, modulation iscarried out in the form of multi-pulses between recording power (peakpower) and bias power 3. In the present embodiment, in any of the Hformat and B format systems, a minimum mark length relevant to a channelbit length T is obtained as 2 T. In the case where this minimum mark of2 T is recorded, one write pulse of recording power (peak power) afterbias power 1 is used as shown in FIG. 18, and bias power 2 istemporarily obtained immediately after the write pulse. In the casewhere a 3 T recording mark 9 is recorded, bias power 2 is temporarilyused after exposing two write pulses, a first pulse and a last pulse ofrecording power (peak power) level that follows bias power 1. In thecase where a recording mark 9 having a length of 4 T or more isrecorded, bias power 2 is used after multi-pulse and write pulseexposure.

The vertical dashed line in FIG. 18 shows a channel clock cycle. In thecase where a 2 T minimum mark is recorded, the laser power is risen at aposition delayed by T_(SFP) from a clock edge, and fallen at a position,which is backward by T_(ELP) from an edge of a succeeding clock. A cycleduring which the laser power is set at bias power 2 is defined asT_(LC). Values of T_(SFP), T_(ELP), and T_(LC) are recorded in physicalformat information PFI contained in a control data zone CDZ as describedlater in the case of the H format. In the case where a 3 T or more longrecording mark is formed, the laser power is risen at a position delayedby T_(SFP) from a clock edge, and lastly, ended with a last pulse.Immediately after the last pulse, the laser power is kept at the biaspower 2 during a period of T_(LC). Shift times from a clock edge to arise/fall timing of the last pulse are defined as T_(SLP), T_(ELP). Inaddition, a shift time from a clock edge to a fall timing of the lastpulse is defined as T_(EFP), and further, an interval of a single pulseof a multi-pulse is defined as T_(MP).

Each of intervals T_(ELP)-T_(SFP), T_(MP), T_(ELP)-T_(SLP), and T_(LC)is defined as a half-value wide relevant to a maximum value, as shown inFIG. 19. In addition, in the present embodiment, the above parametersetting range is defined as follows:0.25 T≦T _(SFP)≦1.50 T  (30)0.00 T≦T _(ELP)≦1.00 T  (31)1.00 T≦T _(EFP)≦1.75 T  (32)−0.10 T≦T _(SLP)≦1.00 T  (33)0.00 T≦T _(LC)≦1.00 T  (34)0.15 T≦T _(MP)≦0.75 T  (35)

Further, in the present embodiment, the values of the above describedparameters can be changed as shown in FIGS. 20A, 20B and 20C accordingto a recording mark length (Mark Length) and the immediatelypreceding/immediately succeeding space length (Leading/Trailing spacelength). FIGS. 21A, 21B and 21C each shows parameter values when optimalrecording power of the write-once type information storage mediumrecorded in a principle of recording shown in the present embodiment hasbeen checked, as described in the section “3-3) Recordingcharacteristics common to organic dye recording film in the presentembodiment”. At this time, the values of bias power 1, bias power 2, andbias power 3 are 2.6 mW, 1.7 mW, and 1.7 mW, and reproduction power is0.4 mW.

Chapter 5: Specific Description of Organic Dye Recording Film in thePresent Embodiment

5-1) Description of characteristics relating to “L-H” recording film inthe present embodiment

A description will be given with respect to an “L-H” recording filmhaving characteristics in which a light reflection amount is lowered ina recording mark as compared with that in an unrecorded area. From amongprinciples of recording described in “3-2-B] Basic characteristicscommon to organic dye recording material in the present embodiment”, aprinciple of recording in the case of using this recording film mainlyutilizes any of:

Chromogenic characteristic change;

Change of electron structure (electron orbit) relevant to elements whichcontribute to chromogenic phenomenon [discoloring action or the like];and

Array change between molecules, and changes characteristics of lightabsorption spectra. The “L-H” recording film is featured in that thereflection amount range in an unrecorded location and a recordedlocation has been specified in view of characteristics of a read-onlytype information storage medium having a one-sided two-layeredstructure. FIG. 22 shows a light reflection factor range in anunrecorded area (non-recording portion) of the “H-L” recording film andthe “L-H” recording film according to the present embodiment. In thepresent embodiment, the lower limit value δ of the reflection factor atthe non-recording portion of the “H-L” recording film is specified so asto be higher than an upper limit value γ at the non-recording portion ofthe “L-H” recording film. When the above information storage medium hasbeen mounted on an information recording/reproducing apparatus or aninformation reproducing apparatus, a light reflection factor of thenon-recording portion is measured by the slice level detector unit 132or the PR equalizer circuit 130 shown in FIG. 11, thereby making itpossible to judge whether the film is the “H-L” recording film or “L-H”recording film, and thus, making it very easy to judge type of recordingfilm. Measurement has been carried out while producing the “H-L”recording film and the “L-H” recording film under a changedmanufacturing condition, when a light reflection factor α between thelower limit value δ at the non-recording portion of the “H-L” recordingfilm and the upper limit value γ at the non-recording portion of the“L-H” recording film is set in the range of 32% to 40%. As a result, ithas been found that high manufacturing performance of the recording filmis obtained and medium cost reduction is facilitated. After an opticalreflection factor range 801 of a non-recording portion (“L” portion) ofthe “L-H” recording film is made coincident with a light reflectionfactor range 803 of a one-sided double recording layer in the read-onlytype information storage medium, when a light reflection factor range802 of a non-recording portion (“H” portion”) of the “H-L” recordingfilm is made coincident with a light reflection factor range 804 of aone-sided single layer in the read-only type information storage medium,a reproducing circuit of the information reproducing apparatus can beused in common to be well compatible with the read-only type informationstorage medium, and thus, the information reproducing apparatus can beproduced inexpensively. Measurement has been carried out while producingthe “H-L” recording film and the “L-H” recording film under a variety ofchanged manufacturing conditions, in order to facilitate price reductionof a medium while improving the manufacturing performance of therecording film. As a result, the lower limit value β of the lightreflection factor of the non-recording portion (“L” portion) of the“L-H” recording film is set to 18%, and the upper limit value γ is setto 32%; and the lower limit value δ of the light reflection factor ofthe non-recording portion (“H” portion) of the “H-L” recording film isset to 40%, and the upper limit value ε is set to 85%.

FIGS. 23 and 24 show reflection factors at a non-recording position anda recorded position in a variety of recording films in the presentembodiment. In the case where an H format has been employed (refer to“Chapter 7: Description of H Format”), an optical reflection factorrange at the non-recording portion is specified as shown in FIG. 22,whereby a signal appears in a same direction in an emboss area (such assystem leas-in area SYLDI) and a recording mark area (data lead-in areaDTLDI, data lead-out area DTLDO, or data area DTA) in the “L-H”recording film while a groove level is defined as a reference.Similarly, in the “H-L” recording film, while a groove level is definedas a reference, a signal appears in an opposite direction in an embossarea (such as system lead-in area SYSDI) and a recording mark area (datalead-in area DTLDI, data lead-out area DTLDO, or data area DTA).Utilizing this phenomenon, a detecting circuit design corresponding tothe “L-H” recording film and “H-L” recording film is facilitated inaddition to use for recording film identification between the “L-H”recording film and the “H-L” recording film. In addition, thereproduction signal characteristics obtained from a recording markrecorded on the “L-H” recording film shown in the present embodiment isadjusted to conform to signal characteristics obtained from the “H-L”recording film to meet formulas (20) to (23). In this manner, in thecase of using either one of the “L-H” recording film and the “H-L”recording film, the same signal processor circuit can be used, and thesignal processor circuit can be simplified and reduced in price.

5-2) Characteristics of light absorption spectra relating to “L-H”recording film in the present embodiment

As has been described in “3-4) Description of characteristics relatingto “H-L” recording film in the present embodiment, the relativeabsorbance in an unrecorded area is basically low in the “H-L” recordingfilm, and thus, when reproduction light has been irradiated at the timeof reproduction, there occurs an optical characteristic change generatedby absorbing energy of the reproduction light. Even if an opticalcharacteristic change (update of recording action) has occurred afterthe energy of the reproduction light has been absorbed in a recordingmark having high absorbance, a light reflection factor from therecording mark is lowered. Thus, reproduction signal processing is lessaffected because such a change works in a direction in which anamplitude of a reproduction signal (I₁₁≡I_(11H)−I_(11L)) of thereproduction signal increases.

In contrast, the “L-H” recording film has optical characteristics that“a light reflection factor of an unrecorded portion is lower than thatin a recording mark”. This means that, as is evident from the contentsdescribed with respect to FIG. 2B, the absorbance of the unrecordedportion is higher than that in the recording mark. Thus, in the “L-H”recording film, signal degradation at the time of reproduction is likelyto occur as compared with the “H-L” recording film. As described in“3-2-B] Basic characteristics common to organic dye recording materialin the invention”, there is a need for improving reliability ofreproduction information in the case where reproduction signaldegradation has occurred due to ultraviolet ray or reproduction lightirradiation”.

As a result of checking the characteristics of an organic dye recordingmaterial in detail, it has been found that a mechanism of absorbing theenergy of reproduction light to cause an optical characteristic changeis substantially analogous to that of an optical characteristic changedue to ultraviolet ray irradiation. As a result, if there is provided astructure of improving durability relevant to ultraviolet rayirradiation in an unrecorded area, signal degradation at the time ofreproduction hardly occurs. Thus, the present embodiment is featured inthat, in the “L-H” recording film, a value of λ_(max write) (maximumabsorption wavelength which is the closest to wavelength of recordinglight) is longer than a wavelength of recording light or reproductionlight (close to 405 nm). In this manner, the absorbance relevant to theultraviolet ray can be reduced, and the durability relevant toultraviolet ray irradiation can be significantly improved. As is evidentfrom FIG. 26, a difference in absorbance between a recorded portion andan unrecorded portion in the vicinity of λ_(max write) is small, and adegree of reproduction signal modulation (signal amplitude) in the casewhere the wavelength light in the vicinity of λ_(max write) is reduced.In view of a wavelength change of a semiconductor laser light source, itis desirable that a sufficiently large degree of reproduction signalmodulation (signal amplitude) be taken in the range of 355 nm to 455 nm.Therefore, in the present embodiment, a design of a recording film 3-2is made so that a wavelength of λ_(max write) exists out of the range of355 nm to 455 nm (i.e., at a longer wavelength than 455 nm).

FIG. 25 shows an example of light absorption spectra in the “L-H”recording film in the present embodiment. As described in “5-1)Description of features relating to “L-H” recording film, a lower limitvalue β of a light reflection factor at a non-recording portion (“L”section) of the “L-H” recording film is set to 18%, and an upper limitvalue γ is set to 32% in the present embodiment. From 1−0.32=0.68, inorder to meet the above condition, it is possible to intuitivelyunderstand whether or not a value Al₄₀₅ of the absorbance in anunrecorded area at 405 nm should meet:Al ₄₀₅≧68%  (36)

Although the light reflection factor at 405 nm of the light reflectionlayer 4-2 in FIGS. 2A and 2B is slightly lowered than 100%, it isassumed that the factor is almost close to 100% for the sake ofsimplification. Therefore, the light reflection factor when absorbanceAl=0 is almost 100%. In FIG. 25, the light reflection factor of thewhole recording film at a wavelength of λ_(max write) is designated byRλ_(max write). At this time, assuming that the light reflection factoris zero (Rλ_(max write)≈0), formula (36) is derived. However, inactuality, the factor is not set to “0”, and thus, it is necessary todrive a severer formula. A severe conditional formula for setting theupper light value γ of the light reflection factor of the non-recordingportion “L” portion) of the “L-H” recording film to 32% is given by:1−Al ₄₀₅×(1−Rλ _(max write))≦0.32  (37)

In a conventional write-once type information storage medium, only the“H-L” recording film is used, and there is no accumulation ofinformation relating to the “L-H” recording film. However, in the caseof using the present embodiment described later in “5-3) Anion portion:azo metal complex+cation portion: dye” and “5-4) Using “copper” as azometal complex+center metal”, the most severest condition which meetsformula (37) is obtained as:Al ₄₀₅≧80%  (38)

In the case of using an organic dye recording material described laterin the embodiment, when an optical design of a recording film is madeincluding a margin such as a characteristic variation at the time ofmanufacture or a thickness change of the recording layer 3-2, it hasbeen found that a minimum condition which meet the reflection factordescribed in the section “Description of featured relating to “L-H”recording film” in the present embodiment:Al ₄₀₅≧40%  (39)

may be met. Further, by meeting either of:Al ₃₅₅≧40%  (40)Al ₄₅₅≧40%  (41)

it is possible to ensure stable recording characteristics orreproduction characteristics even if a wavelength of a light source ischanged in the range of 355 nm to 405 nm or in the range of 405 nm to455 nm (in the range of 355 nm to 455 nm in the case where both of theformulas are met at the same time).

FIG. 26 shows a light absorption spectrum change after recorded in the“L-H” recording film according to the present embodiment. It isconsidered that a value of a maximum absorption wavelength λI_(max) in arecording mark deviates from a wavelength of λ_(max write), and aninter-molecular array change (for example, an array change between azometal complexes) occurs. Further, it is considered that a discoloringaction (cutting of local electron orbit (local molecular linkdissociation)) occurs in parallel to a location in which both of theabsorbance in location of λl_(max) and the absorbance Al₄₀₅ at 405 nmare lowered and the light absorption spectra spreads itself.

In the “L-H” recording film according to the present embodiment as well,by meeting each of formulas (20), (21), (22), and (23), the same signalprocessor circuit is made available for both of the “L-H” recording filmand the “H-L” recording film, thereby promoting simplification and pricereduction of the signal processor circuit. In formula (20), when:I ₁₁ /I _(11H)≡(I _(11H) −I _(11L))/I _(11H)≧0.4  (42),is modified,I _(11H) ≧I _(11L)/0.6  (43)

is obtained. As described previously, in the present embodiment, a lowerlimit value β of a light reflection factor of an unrecorded portion (“L”portion) of an “L-H” recording film is set to 18%, and this valuecorresponds to I_(11L). Further, conceptually, the above valuecorresponds to:I _(11H)≈1−Ah ₄₀₅×(1−Rλ _(max write))  (44).

Thus, from formulas (43) and (44), the following formula is established:1−Ah ₄₀₅×(1−Rλ _(max write))≧0.18/0.6  (45)

If 1−Rλ_(max write)≈0, formula (45) is modified as follows:Ah ₄₀₅≦0.7  (46)

In comparison between the above formulas (46) and (36), it is found thatthe values of Al₄₀₅ and Ah₄₀₅ may be seemingly set in the vicinity of68% to 70% as values of absorbance. Further, in view of a case in whichthe value of Al₄₀₅ is obtained in the range of formula (39) andperformance stability of a signal processor circuit, a sever conditionis obtained as:Ah ₄₀₅≦0.4  (47)

If possible, it is desirable to meet;Ah ₄₀₅≦0.3  (48)

5-3) Anion portion: Azo metal complex+cation portion: dye

A description will be specifically given with respect to an organic dyematerial in the present embodiment having characteristics described in“5-1) Description of characteristics relating to “L-H” recording film inthe present embodiment”, the present embodiment meeting a conditionshown in “5-2) Characteristics of optical absorption spectra relating to“L-H” recording film” in the present embodiment”. The thickness of therecording layer 3-2 meets the conditions shown in formulas (3), (4),(27), and (28), and is formed by spinner coating (spin coating). Forcomparison, a description will be given by way of example. A crystal ofa “salt” is assembled by “ion coupling” between positively charged“sodium ions” and negatively charged “chloride ions”. Similarly, inpolymers as well, there is a case in which a plurality of polymers arecombined with each other in the form close to “ion coupling”, formingconfiguring an organic dye material. The organic dye recording film 3-2in the present embodiment is composed of a positively charged “cationportion” and a negatively charged “anion portion”. In particular, theabove recording film is technically featured in that: coupling stabilityis improved by utilizing a “dye” having chromogenic characteristics forthe positively charged “cation portion” and utilizing an organic metalcomplex for the negatively charged “anion portion”; and there is met acondition that “δ] an electron structure in a chromogenic area isstabilized, and structural decomposition relevant to ultraviolet ray orreproduction light irradiation hardly occurs” shown in “3-2-B] Basicfeature common to organic dye recording material in the presentembodiment”. Specifically, in the present embodiment, an “azo metalcomplex” whose general structural formula is shown in FIG. 3 is utilizedas an organic metal complex. In the present embodiment which comprises acombination of an anion portion and a cation portion, cobalt or nickelis used as a center metal M of this azo metal complex, thereby enhancingoptical stability. There may be used: scandium, yttrium, titanium,zirconium, hafnium, vanadium, niobium, tantalum, chrome, molybdenum,tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium,rhodium, iridium, palladium, platinum, copper, silver, gold, zinc,cadmium, or mercury and the like without being limited thereto. In thepresent embodiment, as a dye used for the cation portion, there is usedany of a cyanine dye whose general structural formula is shown in FIG.27; a styril dye whose general structural formula is shown in FIG. 28;and a monomethine cyanine dye whose general structural formula is shownin FIG. 29.

Although an azo metal complex is used for the anion portion in thepresent embodiment, a formazane metal complex whose general structuralformula is shown in FIG. 30 may be used without being limited thereto,for example. The organic dye recording material comprising the anionportion and cation portion is first powdered. In the case of forming therecording layer 3-2, the powdered organic dye recoding material isdissolved in organic solvent, and spin coating is carried out on thetransparent substrate 2-2. At this time, the organic solvent to be usedincludes: a fluorine alcohol based TFP (tetrafluoro propanol) orpentane; hexane; cyclohexane; petroleum ether; ether or analogous,nitrile or analogous, and any of a nitro compound or sulfur-containingcompound or a combination thereof.

5-4) Using “copper” as azo metal complex+center metal

FIGS. 65 and 66 each show an example of a light spectrum change beforeand after recording (forming a recording mark) in an “H-L” recordingfilm and an “L-H” recording film using an optical characteristic changeaccording to the present embodiment as a principle of recording. Awavelength of λ_(max write) before recording (in an unrecorded area) isdefined as λb_(max write); a half value width of a light absorptionspectrum (b) around this λ_(max write) (a width of a wavelength areameeting a range of “A≧0.5” when the absorbance A at λb_(max write) is“1”) is defined as W_(as); and a wavelength of λ_(max write) of a lightabsorption spectrum (a) after recorded (in a recording mark) is definedas λa_(max write). The recording film 3-2 having the characteristicsshown in FIGS. 65 and 66 utilizes a “change of an electron structure(electron orbit) relevant to elements which contribute to a chromogenicphenomenon and a “molecular structure change in molecules” from amongthe principles of recording shown in [α] of “3-2-B] Basiccharacteristics common to organic dye recording material in theinvention”. If there occurs a “change of an electron structure (electronorbit) relevant to electrons which contribute to a chromogenicphenomenon”, for example, the dimensions or structure of the lightemitting area 8 as shown in FIG. 3 changes. For example, if dimensionsof the light emitting area 8 change, the resonant absorption wavelengthof the local electrons also changes, and thus, the maximum absorptionwavelength of light absorption spectra changes from λb_(max write) toλa_(max write). Similarly, if a “molecular structure change inmolecules” occurs, a structure of the light emitting area 8 alsochanges, and thus, the maximum absorption wavelength of the lightabsorption spectra also changes. When a change amount of the maximumabsorption wavelength is defined as Δλ_(max), the following relationshipis established:Δλ_(max) ≡|λa _(max write) −λb _(max write)|  (49)

When the maximum absorption wavelength of the light absorption spectrathus changes, the half value width W_(as) of the light absorptionspectra also changes concurrently. A description will be given withrespect to an effect on a reproduction signal obtained from a recordingmark position when the maximum absorption wavelength of the lightabsorption spectra and the half value width W_(as) of the lightabsorption spectra have thus changed at the same time. The lightabsorption spectra in a pre-recording/unrecorded area are represented as(b) in FIG. 65 (FIG. 66), and thus, the absorbance with a reproductionlight beam having 405 nm is obtained as Ah₄₀₅ (Al₄₀₅). If only themaximum absorption wavelength changes to λa_(max write) as opticalspectra after recorded (in recording mark) and a change of the halfvalue width W_(as) has not occurred, the light absorption spectra aretheoretically obtained as shown in (c) of FIG. 65 (FIG. 66). Then, theabsorbance with a reproduction light beam having 405 nm changes toA*₄₀₅. However, in actuality, the half value width changes, and theabsorbance after recorded (in recording mark) is obtained as Al₄₀₅(Ah₄₀₅). A change amount |Al₄₀₅−Ah₄₀₅| of the absorbance before andafter recorded is proportional to a reproduction signal amplitude value.Thus, in the example shown in FIG. 65 (FIG. 66), the maximum absorptionwavelength change and the half width value change work as an offsetaction relevant to an increase of the reproduction signal amplitude.Therefore, there occurs a problem that a C/N ratio of a reproductionsignal is impaired. A first application example of the presentembodiment for solving the above problem is featured in that thecharacteristics of the recording layer 3-2 is set (film-designed) sothat a maximum absorption wavelength change and a half value widthchange work relevant to an increase of the reproduction signal amplitudein a synergetic manner. That is, as is easily predicted from the changeshown in FIG. 65 (FIG. 66), the characteristics of the recording layer3-2 is set (film-designed) so that a change occurs in a direction inwhich a half value width widens independent of a moving direction ofλa_(max write) after recorded relevant to λb_(max write) before recordedin the “H-L” recording film or in a direction in which the half valuewidth narrows independent of a moving direction of λa_(max write) afterrecorded relevant to λb_(max write) before recorded in the “L-H”recording film.

Now, a second application example in the present embodiment will bedescribed here. As described previously, there is a case in which theC/N ratio of the reproduction signal is lowered by offsetting adifference between Ah₄₀₅ and Al₄₀₅ due to the maximum absorptionwavelength change and the change of the half value width W_(as).Further, in the above first application example or the embodiment shownin FIG. 65 or FIG. 66, the maximum absorption wavelength change and thehalf value width W_(as) of the light absorption spectra change at thesame time, a value of the absorbance “A” after recorded (in recordingmark) is affected by both of the maximum absorption wavelength changeamount Δλ_(max) and the half value width change amount. When thewrite-once type information storage medium 12 has been mass-produced, itis difficult to precisely control values of both of the maximumabsorption wavelength change amount Δλ_(max) and the half value widthchange amount. Thus, when the information is recorded in themass-produced write-once type information storage medium 12 has beenrecorded, a fluctuation of the reproduction signal amplitude increases.Then, the reliability of the reproduction signal is lowered when thesignal has been reproduced by the information reproducing apparatusshown in FIG. 11. In contrast, the second application example in thepresent embodiment is featured in that a material of which the maximumabsorption wavelength does not change between before and after recorded(between the recording mark and the unrecorded area). Therefore, afluctuation of values of the absorbance “A” after recorded (in recordingmark) is suppressed and a fluctuation between the individuals of thereproduction signal amplitude from the above value fluctuation isreduced, whereby the reliability of the reproduction signal has beenimproved. In this second application example, the maximum absorptionwavelength does not change between before and after recording (inrecording mark and in unrecorded area), and the value of the absorbance“A” is determined depending on only the spread of the light absorptionspectra before and after recording (in recording mark and in unrecordedarea). When a large number of write-once type information storagemediums 12 have been mass-produced, it is sufficient if only the spreadof the light absorption spectra before and after recorded (in recordingmark and in unrecorded area) is controlled, and thus, a fluctuation incharacteristics between mediums can be reduced. Even if a contrivance ismade so that a maximum absorption wavelength before and after recording(in recording mark and in unrecorded area) does not change, strictly, itis difficult to completely match the values of λb_(max write) andλa_(max write) each other, as shown in FIG. 68. The half value widthW_(as) of the light absorption spectra around λb_(max write) shown inFIG. 65 or 66 is often included in the range of 100 nm to 200 nm in ageneral organic dye recording material. Therefore, if the value of themaximum absorption wavelength change amount Δλ_(max) exceeds 100 nm, itis possible to easily predict from FIG. 65 or 66 that there occurs alarge difference between the absorbance Ah₄₀₅ (Al₄₀₅) obtained from thecharacteristics of item (b) and the absorption A*₄₀₅ obtained from thecharacteristics of item (c). Accordingly, the fact that “the maximumabsorption wavelength does not change” as the second application examplemans that the following condition is met:Δλ_(max)≦100 nm  (50)

Further, when a condition that the maximum absorption wavelength changeamount Δλ_(max) is ⅓ of the value obtained by formula (50), i.e.,Δλ_(max)≦30 nm  (51)

a difference between the absorbance Ah₄₀₅ (Al₄₀₅) obtained from thecharacteristics of item (b) and the absorption A*₄₀₅ obtained from thecharacteristics of item (c) is very small, and a fluctuation inreproduction signal characteristics between the mediums can be reduced.

FIG. 68 shows the “L-H” recording film characteristics, which meetformula (50) or formula (51). The light absorption spectra beforerecorded (in unrecorded area) are obtained as wide spectra as shown inthe characteristic (b) of FIG. 68, and the absorbance Ah₄₀₅ at areproduction wavelength of 405 nm is obtained as a sufficient smallvalue. The absorbance Ah₄₀₅ after recorded (in recording mark) narrowsin width as shown in the characteristic (a) of FIG. 68, and theabsorbance Al₄₀₅ at a reproduction wavelength of 405 nm rises.

In order to meet formula (50) or formula (51), the present embodimentutilizes an “orientation change in molecules” in item [α] of “3-2-B]Basic characteristics common to organic dye recording material in theinvention” as a principle of recording. In the azo metal complex shownin FIG. 3, a plurality of benzene nucleus rings are located on the sameplane because the benzene nucleus rings are radically coupled with eachother. That is, in FIG. 3, four benzene nuclear rings which exist moreupwardly than the center metal M forms an U (up-side) plane which thebenzene nucleus group produced; and four benzene nuclear rings L whichexist more downwardly than the center metal M forms a D (down-side)plane which the benzene nucleus group produced.

A mutually parallel relationship is always maintained between the aboveU plane and D plane in any case (irrespective of whether pre-recordingor post-recording may be). Side chain groups of R1 and R3 are arrangedin a form orthogonal to the above U plane and D plane. Ion coupling iscarried out between the center metal atom M and the oxygen atom O, and aplane formed by a line segment for connecting O-M-O is located inparallel to the above U plane and D plane. The light emitting area 8surrounded in a round area shown in FIG. 3 has such a three-dimensionalstructure. For further description, a direction oriented from adirection of R4 to a direction of R5 in the U plane is tentativelydefined as a “Yu direction”, and a direction oriented from a directionof R4 to a direction of R5 in the D plane is defined as a “Yddirection”. Orientation coupling is carried out between a nitrogen atomN included in the U plane or D plane and the center metal atom Msandwiched between these two planes so that a position of the nitrogenatom N around the center metal atom M can be rotated. That is, astructure is provided such that the Yd direction can be rotated withrespect to the Yu direction while a mutually parallel relationship ismaintained between the above U plane and D plane. In the azo metalcomplex shown in FIG. 3, the Yu direction and Yd direction can beparallel to each other, as shown in FIG. 67A (the orientations can bemade identical or opposite to each other as shown in FIG. 67A); and theYu direction and Yd direction can be in a skew position relationship asshown in FIG. 67B. Of course, an arbitrary angle relationship betweenFIGS. 67A and 67B can be also established. As described previously, theside chain groups of R1 and R3 are arranged in a form orthogonal to theabove U plane and D plane. Thus, in the structure of FIG. 67A, collisionis likely to occur between the side chain group of R1 or R3 and anotherside chain group of R4 or the like. Therefore, as shown in FIG. 67B, atime point at which the Yu direction and Yd direction are in a skewposition relationship (when the U plane is seen from far above, the Yudirection and Yd direction are seen as if it were orthogonal to eachother) is the most stable in a structural point of view. The lightabsorption wavelength in the light emitting area 8 when the state shownin FIG. 67B is established coincides with a value ofλa_(max write)=λb_(max write) shown in FIG. 68. If the relationshipbetween the Yu direction and Yd direction deviates from the state shownin FIG. 67B, the electron structure in the light emitting area 8 and thelocal distance of light absorption electrons (the size of local area)slightly change, and the light absorption wavelength deviates from thevalue of λa_(max write)=λb_(max write). By means of spinner coating, arelationship between the above Yu direction and Yd direction isarbitrarily oriented in the recording layer 3-2 (in unrecorded state)immediately after formed on the transparent substrate 2-2. Therefore,the distribution width of light absorption spectra widens as shown incharacteristic (b) of FIG. 68. In order to form a recording mark, when atemperature in the recording layer 3-2 is locally risen, a molecularorientation moves because of a high temperature, and finally, an almoststable state shown in FIG. 67B is established in a structural point ofview. Then, the electron structures in the light emitting area 8coincide with each other anywhere in the recording mark, and the currentspectra changes to narrow light absorption spectra in width, as shown incharacteristic (a) of FIG. 68. As a result, the absorbance at areproduction wavelength (for example, 405 nm) changes from Al₄₀₅ toAh₄₀₅.

A description will be made with respect another advantageous effect ofusing the light emitting area 8 in an azo metal complex. A dye isutilized for a cation portion in the case of utilizing a combination ofthe anion portion and the cation portion described previously. Althoughthe chromogenic area in each of the dyes shown in FIGS. 27 to 29occupies a portion in each of the dye structures, a relative occupyingcapacitance of the chromogenic area in the recording layer 3-2 isdecreased by combining this area with an anion portion which does notcontribute to the chromogenic area. Therefore, a light absorptionsectional area is relatively lowered, and a molar molecule lightabsorption coefficient is lowered. As a result, a value of theabsorbance at a position of λ_(max write) shown in FIG. 25 is reduced,and recording sensitivity is lowered. In contrast, in the case ofutilizing the chromogenic characteristics at the periphery of the centermetal of an azo metal complex itself described here, the azo metalcomplex itself emits light, and thus, there does not exist a redundantportion which does not contribute to a chromogenic area such as theanion portion described previously. Therefore, there is no unnecessaryfactor that the relative occupying capacitance of the chromogenic areadecreases. Further, as shown in FIG. 3, the occupying capacitance of thelight emitting area 8 in the azo metal complex is wide, and thus, thelight absorption sectional area increases, and a value of the molarmolecule light absorption coefficient rises. As a result, there isprovided advantageous effect that the value of the absorbance at aposition of λ_(max write) shown in FIG. 25 increases, and the recordingsensitivity is improved.

The present embodiment is featured in that the structural stability ofthe chromogenic area has been achieved by optimizing the center metal ofthe azo metal complex as a specific method for “δ] stabilizing anelectron structure in a chromogenic area so that structuraldecomposition relevant to ultraviolet ray or reproduction lightirradiation hardly occurs” described in “3-2-B] Basic characteristicscommon to organic dye recording material in the invention”.

It is known that metal ions have their unique ionization tendency. Thesemetal atoms are arranged in stronger order of ionization tendency, i.e.,Na>Mg>Al>Zn>Fe>Ni>Cu>Hg>Ag>Au. The ionization tendency of the metalatoms represents “nature of metal radiating electrons to form positiveions”.

After a variety of metal atoms has been incorporated as the center metalof the azo metal complex having the structure shown in FIG. 3, wherereproduction stability (stability of chromogenic characteristics when alight beam in the vicinity of 405 nm is repeatedly irradiated withreproduction power) is repeatedly checked, it has been found that themetal atoms with high ionization tendency radiates electrons moreremarkably and are easily decoupled; and the light emitting area 8 iseasily destroyed. As a result of a number of tests, in order to ensurestructural stabilization of the chromogenic area, it has been founddesirable to use a metal material (Ni, Cu, Hg, Ag, Au) after nickel (Ni)as the center metal. Further, from the viewpoint of “structuralstability of high chromogenic area”, “low price”, and “use safety”, itis the most desirable to use copper (Cu) as the center metal as thepresent embodiment. In the present embodiment, any of CH₃, CxHy, H, Cl,F, NO₂, SO₂, and SO₂NHCH3 is used as R1, R2, R3, R4, or R5 which is aside chain shown in FIG. 3.

Now, a description will be given with respect to a method for forming anorganic dye recording material having a molecular structure shown inFIG. 3 as the recording layer 3-2 on a transparent substrate 2-2. Thepowdered organic dye recording material of 1.49 g is dissolved in 100 nmof TFP (tetrafluoro propanol) which is a fluorine alcohol based solvent.The above numeric value denotes that 1.4 wt % is obtained as a mixtureratio, and an actual use amount changes depending on a manufactureamount of the write-once type information storage medium. It isdesirable that the mixture ratio ranges from 1.2 wt % to 1.5 wt %. As asolvent, it is conditionally mandatory that a surface of the transparentsubstrate 2-2 made of a polycarbonate resin is not dissolved, and theabove described alcohol based solvent is used. Because the above TFP(tetrafluoro propanol) has polarity, the solubility of the powderedorganic dye recording material is improved. While the transparentsubstrate 2-2 on a spindle motor is rotated, the organic dye recordingmaterial dissolved in the solvent is applied to the center part of thetransparent substrate 2-2 until the solvent has evaporated after thematerial has been spread by utilizing a centrifugal force, and then, therecording layer 3-2 is compressed in accordance with a baking processfor increasing the entire temperature.

FIG. 69 shows a third application example in which a basic principle ofthe second application example in the present embodiment is applied tothe “H-L” recording film. The maximum absorption wavelengthλa_(max write) of absorption spectra (a) after recorded (in recordingmark) is equalized with respect to the maximum absorption wavelengthλb_(max write) of absorption spectra (b) before recorded (in unrecordedarea). As an example of a specific organic dye material which achievesthe third application example, an azo metal complex is used for an anionportion. For a cation portion, there is used an “anion/cation typeorganic dye recording material” utilizing dye molecules having anabsorption wavelength λb_(max write) on a shorter wavelength side than areproduction signal wavelength (for example, 405 nm), as shown in FIG.69. In this case, in the azo metal complex shown in FIG. 3, at an αposition or a γ position in the D plane, which a benzene nucleus groupproduces and a β position or a δ position in the U plane which a benzenenucleus group produces, color dye molecules (positively charged cationportion) are allocated by an inter-ion force. As in the secondapplication example, a principle of changing (recording) the lightabsorption spectra before and after recorded while keeping unchanged themaximum absorption wavelength λb_(max write) of the light absorptionspectra (b) before recorded (in unrecorded area) and the maximumabsorption wavelength λa_(max write) of the light absorption spectra (a)after recorded (in recording mark) utilizes rotation between the U plane(Yu direction) which the benzene nucleus group produces and the D plane(Yd direction) which the benzene nucleus group produces. Further, in thethird application example, the electron coupling force in the lightemitting area 8 is improved, whereby “degradation of an electronstructure (electron orbit) with respect to electrons which contribute toa chromogenic phenomenon” hardly occurs. As a result, an area in theabsorption spectra (b) before recorded (in unrecorded area) (anintegration result in spectra wavelength direction) can be adjusted toconform to an area in the absorption spectra (a) after recorded (inrecoding mark). In this manner, the absorbance “A” at the maximumabsorption wavelength λa_(max write) in the absorption spectra (a) afterrecorded (in recording mark) becomes greater than the absorbance “l” atthe maximum absorption wavelength λb_(max write) before recorded (inunrecorded area), and a value of Al₄₀₅ rises more significantly than avalue of Ah₄₀S, as shown in FIG. 69.

In the case where degradation in the light emitting area 8 such asdiscoloring action does not occur, the area in the absorption spectrabefore and after recorded (the integration result in the spectrawavelength direction) is kept unchanged. Thus, the absorbance Aa_(max)in the maximum absorption wavelength λa_(max write) increases with adecrease in the width of the absorption spectra before and afterrecorded. When a difference clearly occurs between the value of theabsorbance Al₄₀₅ and the value of Ah₄₀₅ at the reproduction wavelengthof 405 nm (when a reproduction signal can be detected at a good C/Nratio), from FIG. 69, it is found necessary to meet a condition that thevalue of the absorbance Aa_(max) in the maximum absorption wavelengthλa_(max write) is:Aa _(max)≧1.2  (52)

Further, in order to stably ensure the reliability of reproduction of adetection signal, it is necessary to meet a condition:Aa _(max)>1.5  (53)

Although there has been shown an example of providing a structure inwhich an azo metal complex is utilized for an anion portion and dyes areutilized for a cation portion as a specific organic dye recordingmaterial which achieve the third application example, the invention(third application example) include an organic dye recording materialhaving “H-L” recording characteristics; meeting formula (50) or formula(51) with respect to the maximum absorption wavelength change amountbefore and after recorded; and changing the absorbance at the maximumabsorbance wavelength without being limited thereto, as the specificorganic dye recording material which achieves the third applicationexample.

Further, a fourth application example is shown in FIG. 70. In a phasechange recording film, “atoms are allocated in order (in crystallinestate) before recorded”, and “atoms are arranged in random (in amorphousstate) after recorded”. In the fourth application example, a feature ofthis phase change recording film is combined with a feature that “themaximum absorption wavelength does not change before and after recorded”shown in the second application example. Although a specific organic dyerecording material in the fourth application example has a structure ofutilizing the azo metal complex shown in the third application examplefor an anion portion and dyes for a cation portion as a specific organicrecording material in the fourth application example, the detailedcontained atoms, these application examples are different from eachother in terms of detailed contained atoms, detailed intra-molecularstructure, or a method for manufacturing the recording layer 3-2. Thatis, a time required for solidification of the recording layer 3-2 istaken by using an organic solvent which hardly evaporates after applyingan organic dye recording material dissolved in an organic solvent on thetransparent substrate 2-2 by spinner coating, or alternatively, atemperature of the transparent substrate 2-2 is increased in advance atthe time of the application, and then, the temperature of thetransparent substrate 2-2 is slowly decreased at the time of evaporationof an organic solvent, whereby a contrivance is made so that theintra-molecular (or inter-molecular) orientation or array can be easilyarranged in order at the stage of the solidification of the recordinglayer 3-2. As a result, as shown in characteristic (b) of FIG. 70, thewidth of the light absorption spectra before recorded (in unrecordedarea) becomes narrow. Next, contrivance is made to apply a recordingpulse at the time of recording (for example, after the inside of therecording layer 3-2 has locally exceeded an optical characteristicchange temperature, the width of the recording pulse is narrowed insteadof increasing the height of the recording pulse at the time of applyingthe same energy so as to provide rapid cooling), and the intra-molecular(or inter-molecular) orientation or array after recorded (in recordingmark) is arranged in random. As a result, the width of the lightabsorption spectra after recorded (in recording mark) widens as shown incharacteristic (a) of FIG. 70. A large difference in absorbance “A”before and after recorded is produced by adjusting a reproduction lightwavelength to conform to a lower end position of the light absorptionspectra. Although an example of providing a structure in which an azometal complex is utilized for an anion portion and dyes are utilized fora cation portion as a specific organic dye recording material whichachieve the fourth application example, the invention (fourthapplication example) include an organic dye recording material having“H-L” recording characteristics; meeting formula (50) or formula (51)with respect to the maximum absorption wavelength change amount beforeand after recorded; and changing the absorbance at the maximumabsorbance wavelength without being limited thereto, as the specificorganic dye recording material which achieves the fourth applicationexample.

Chapter 6: Description Relating to Pre-Groove Shape/Pre-Pit Shape inCoating Type Organic Dye Recording Film and on Light Reflection LayerInterface

6-1) Light reflection layer

As described in “Chapter 0: Description of Relationship between UseWavelength and the Present Embodiment”, the present embodiment assumes arange of 355 nm to 455 nm in particular around 405 nm. When the metalmaterials each having a high light reflection factor at this wavelengthbandwidth are arranged in order from the highest light reflectionfactor, Ag is in the order of around 96%; Al is in the order of around80%, and Rh is in the order of around 80%. In a write-one typeinformation storage medium using an organic dye recording material, asshown in FIG. 2B, the reflection light from the light reflection layer4-2 is a standard, and thus, the light reflection layer 4-2 requires ahigh light reflection factor in characteristics. In particular, in thecase of the “H-L” recording film according to the present embodiment,the light reflection factor in an unrecorded area is low. Thus, if thelight reflection factor in the light reflection layer 4-2 simplex islow, in particular, a reproduction signal C/N ratio from a pre-pit(emboss) area is low, lacking the stability at the time of reproduction.Thus, in particular, it is mandatory that the light reflection factor inthe light reflection layer 4-2 simplex is high. Therefore, in thepresent embodiment, in the above wavelength bandwidth, a material mainlymade of Ag (silver) having the highest reflection factor is used. As amaterial for the light reflection layer 4-2, there occurs a problem that“atoms easily move” or “corrosion easily occurs” if silver is usedalone. To solve the first problem, when partial alloying is carried outby adding other atoms, silver atoms hardly move. In the first embodimentin which other atoms are added, the light reflection layer 4-2 is madeof AgNdCu according to the first embodiment. AgNdCu is in a solidsoluble state, and thus, the reflection factor is slightly lowered thana state in which silver is used alone. In the second embodiment in whichother atoms are added, the light reflection layer 4-2 is made of AgPd,and an electric potential is changed, whereby corrosion hardly occurs inan electrochemical manner. If the light reflection layer 4-2 corrodesdue to silver oxidization or the like, the light reflection factor islowered. In an organic dye recording film having a recording filmstructure shown in FIG. 2B, in particular, in the case of an organic dyerecording film shown in “Chapter 3: Description of Characteristics ofOrganic Dye Recording Film in the Present Embodiment”, in particular, alight reflection factor on an interface between the recording layer 3-2and the light reflection later 4-2 is very important. If correctionoccurs on this interface, the light reflection factor is lowered, and anoptical interface shape blurs. In addition, the detection signalcharacteristics from a track shift detection signal (push-pull signal)or a wobble signal and a pre-pit (emboss) area are degraded. Inaddition, in the case where the width Wg of the pre-groove area 11 iswider than the width Wl of the land area, a track shift detection signal(push-pull signal) or a wobble signal is hardly generated, thusincreasing effect of degradation of the light reflection factor on theinterface between the recording layer 3-2 and the light reflection layer4-2 due to corrosion. In order to prevent degradation of the lightreflection factor on this interface, AgBi is used for the lightreflection layer 4-2 as the third embodiment. AgBi forms a very stablephase and prevents degradation of the light reflection factor on theabove interface because a passive coat film is formed on a surface(interface between the recording layer 3-2 and the light reflectionlayer 4-2). That is, if Bi (bismuth) is slightly added to Ag, Bi isisolated from the above interface, the isolated Bi is oxidized. Then, avery fine film (passive coat film) called oxidized bismuth is formed tofunction to preclude internal oxidization. This passive coat film isformed on the interface, and forms a very stable phase. Thus, thedegradation of a light reflection factor does not occur, and thestability of detection signal characteristics from a track shiftdetection signal (push-pull signal) or a wobble signal and a pre-pit(emboss) area is guaranteed over a long period of time. At a wavelengthband ranging from 355 nm to 455 nm, the silver simplex has the highestlight reflection factor, and the light reflection factor is lowered asan additive amount of other atoms is increased. Thus, it is desirablethat an additive amount of Bi atoms in AgBi in the present embodiment beequal to or smaller than 5 at %. The unit of at % used here denotesatomic percent, and indicates that five Bi atoms exist in a total atomnumber 100 of AgBi, for example. When characteristics have beenevaluated by actually producing the passive coat film, it has found thata passive coat film can be produced as long as an additive amount of Biatoms is equal to or greater than 0.5 at %. Based on a result of thisevaluation, an additive amount of Bi atoms in the light reflection layer4-2 in the present embodiment is defined as 1 at %. In this thirdembodiment, only one atom Bi is added, and an additive amount of atomscan be reduced as compared with AgNdCu according to the first embodiment(a case in which two types of atoms Nd and Cu is added in Ag), and AgBican increase the light reflection factor more significantly than AgNdCu.As a result, even in the case of the “H-L” recording film according tothe present embodiment or in the case where the width Wg of thepre-groove area 11 is wider than the with Wl of the land area, as shownin FIGS. 8B and 8C, a detection signal can be stably obtained from atrack shift detection signal (push-pull signal) or a wobble signal and apre-pit (emboss) area with high precision. The third embodiment is notlimited to AgBi, and a ternary system including AgMg, AgNi, AgGa, AgNx,AgCo, AgAl or the atoms described previously may be used as a silverallow which produces a passive coat film. The thickness of this lightreflection layer 4-2 is set in the range of 5 nm to 200 nm. If thethickness is smaller than 5 nm, the light reflection layer 4-2 is notuniform, and is formed in a land shape. Therefore, the thickness of thelight reflection layer 4-2 is set to 5 nm. When an AgBi film is equal toor smaller than 80 nm in thickness, the film permeates to its back side.Thus, in the case of a one-sided single recording layer, the thicknessis set in the range of 80 nm to 200 nm, and preferably, in the range of100 nm to 150 nm. In the case of a one-sided double recording layer, thethickness is set in the range of 5 nm to 15 nm.

Write-once type information storage mediums having high density and usedfor a method for recording information in a storage medium which uses anorganic dye material, the storage mediums carrying out recording andreproduction by using a light beam of 620 nm or less in wavelength,include: a one-sided single-layer medium as shown in FIG. 1B; and aone-sided double-layer medium as shown in FIG. 1C. The one-sidedsingle-layer medium is sequentially composed of a transparent substrate2-2, a recording layer (recording film) 3-2, and a light reflectionlayer (light reflection film) 4-2 from a light incident side. A storagemedium (referred to as L0) close to the light incident side of theone-sided double-layer medium is sequentially composed of thetransparent substrate 2-2, the recording layer 3-2, and a semipermeablelight reflection layer 4-2 from the light incident side. A storagemedium (referred to as L1) distant from the light incident side issequentially composed of the recording layer 3-2, the light reflectionlayer 4-2, and the substrate 2-2 from the light incident side. A layerfor optically separating two layers, a so called interlayer separatinglayer (interlayer separation film) 7-1, is formed between the medium L0and the medium L1. In addition, the transparent substrate 2-2 of themedium L1 may not be always transparent, and an opaque substrate may beused. In the following description, in the case where a layer is merelyreferred to as a light reflection layer, it denotes a generic name ofthe light reflection layer 4-1 and the semipermeable light reflectionlayer 4-2. In order to obtain high signal characteristics on an entiresurface of an optical storage medium, there is a need for providing ahigh reflectivity in a state in which the transparent substrate 2-2, therecording layer 3-2, and the light reflection layer 4-2 have beenlaminated. Thus, it is desirable that a light reflection film simplexhave a high reflectivity. In order to achieve this, a material mainlymade of Ag (silver) having the highest reflectivity is used in the abovewavelength band (405 nm and its proximity, for example, 355 nm to 455nm).

On the other hand, as described in section 6-1), in a silver simplexused as a material for a light reflection film, there occurs a problemthat light reflection characteristics are changed by the fact that“atoms easily move” and “corrosion easily occurs”, and the performanceis degraded in terms of information repetition reproduction, count, andstorage service life. As a means for solving these problems, a methodusing a variety of silver alloys is conventionally known. However, inthe storage medium according to the present invention, there is used anorganic dye recording material which has not been used conventionally.Thus, in the conventional method, the above-described problems have notbeen solved.

A conventionally known method for preventing movement of single silveratoms in a light reflection film includes a method for adding to silveran element which has a pinning effect. On the other hand, there has notbeen clarified an element which prevents movement of single silver atomswithout lowering a reflectivity in the above-described wavelength bandor significantly lowering thermal characteristics. With respect to adisclosed conventional technique, as long as an amount of additives isnot particularly large, there is substantially no advantageous effect.On the other hand, there are two methods for preventing corrosion ofsilver in a reflection film; (1) a electrochemical method; and (2) amethod for forming a passive coat on an interface. With respect to (1)the electrochemical method, as long as an amount of additives is notparticularly large, there is substantially no advantageous effect. Inaddition, with respect to (2) the method for forming the passive coat onthe interface as well, there has not been achieved a method for forminga rigid passive coat without lowering the reflectivity in theabove-described wavelength band or significantly lowering the thermalcharacteristics. This is because, in order to complete a storage mediumembodiment, characteristics greatly depend on what configuration of astorage medium is used, and thus, it is impossible to obtain problems tobe solved and a proper means for solving these problems merely byinvestigating general material characteristics. In addition, in the caseof the present embodiment, in addition to these problems, it has beendifficult to achieve the embodiment by the use of the organic dyerecording material which has not been used conventionally, as describedbelow.

In order to prevent movement of single silver atoms and preventcorrosion of silver in a reflection film without lowering thereflectivity in the above-described waveform band or withoutsignificantly lowering the thermal characteristics, the presentembodiment is featured by a light reflection layer of a storage mediumshown in FIGS. 1B and 1C using an organic dye material recorded with alight beam of 620 nm or less in wavelength in which prevention layers 8,8-1, and 8-2 which prevent a characteristic change of a light reflectionlayer are provided between a light reflection layer and a recordinglayer. The causes for characteristic change are movement of atoms andreaction (corrosion). The reaction used here includes a chemicalreaction or performance degradation caused by a light reflection layercoming into contact with an organic dye material which is a recordingfilm. The prevention layer used here may not be formed to have a finitethickness (passive coat formed on interface), and may be formed as alayer (electrochemical layer) having electrically differentcharacteristics, the layer being formed by a semiconductor apparatus ora semiconductor device and the like.

The light reflection layer used here is composed essentially of silverAg, contains at least one type of additive elements selected from:aluminum Al; gold Au; bismuth Bi; calcium Ca; cerium Ce, cobalt Co,gallium Ga, lanthanum La; magnesium Mg; nitrogen N; nickel Ni; neodiumNd; palladium Pd; yttrium Y; tungsten W, and zirconium Zr, and rangesfrom 0.05 at % to 5 at % in total of additive elements. It is impossibleto avoid entry of a very small amount of elements into Ag and additiveelements used as a base material for a reflection film material. Withrespect to these elements, even if a very small amount thereof isdetected by analysis, it is impossible to say they are a differentmaterial. Therefore, this material is not said to be different from thescope of the present invention.

For example, let us consider a light reflection layer using AgBi. AgBiforms a passive coat on a surface (interface between recording layer 3-2and light reflection layer 4-2). Thus, this element forms a very highstable phase, and prevents degradation of the light reflectivity on theabove-described interface. That is, if a small amount of Bi (bismuth) isadded to Ag, Bi floats on the interface, and is oxidized. Then, a verydelicate film (passive coat) called bismuth oxide is formed, andfunctions to stop internal oxidization or reaction, or alternatively,degradation of the reflection film. In addition, in a combination withthe organic dye recording material used in the present embodiment, ithas been found that there is attained advantageous effect of preventingmovement of single silver atoms without lowering the reflectivity in theabove-described wavelength band or significantly lowering the thermalcharacteristics. In general, the concentration of additive elements inan Ag alloy is greatly influenced by a reflectivity or opticalcharacteristics, thermal characteristics, and easiness of movement ofsingle silver atoms. Therefore, an Ag alloy in which a concentrationchange occurs is considered to be generally low in advantageous effectof preventing movement of single silver atoms without lowering thereflectivity or significantly lowering the thermal characteristics. Inthe present embodiment, it is considered that advantageous effect hasbeen attained in a configuration which seems to have been ineffectiveconventionally because a specific organic dye material is used.Therefore, the present invention is greatly featured by a lightreflection layer of a storage medium using an organic dye materialrecorded with a light beam of 620 nm or less in wavelength in whichthere is formed a prevention layer which prevents reaction between alight reflection layer and a recording layer caused by the lightreflection layer coming into contact with an organic dye material or acharacteristic change or degradation of an optical reflection layer.These advantageous effects are considered as being attained by combiningthe organic dye material and the Ag alloy according to the presentembodiment.

In addition, apart from Bi, it has been found that similar advantageouseffect is attained in Ca, Ce, Co, Ga, Ni, La, Mg, W, and Zr (elementsfor forming a passive coat including Bi is referred to as additiveelements of group 1). On the other hand, in Al, Au, Pd, Pt, and Rh(referred to as additive elements of group 2), electrochemicallyadvantageous effect is strong. Thus, it is effective to use theseadditive elements of group 2 in combination with the additive elementsof group 1. In addition, with respect to N (nitrogen), a reactionproduct with Ag—N serves as part of a passive coat. Thus, the passivecoat may be formed of a plurality of layers without being limited to asingle layer. In addition to the additive elements of group 1, it iseffective to add Cu, Nd, or Y (referred to as additive elements of group3). With respect to group 2, group 3, and N, even if comparatively largeamounts of these elements are added or reacted, no precipitation occurs,and solid solution or reaction with Ag can be obtained. Thus, if anamount of additives increases, the reflectivity or thermal conductivityis rapidly lowered. Therefore, careful consideration is required for theamount of additives and adding process. Among them, for example, in thecase where AgAl is used, if an amount of additives increases, thelowering of the reflectivity and thermal conductivity of the reflectionfilm becomes very substantial.

When the content of additive elements 0.05 at % or less, advantageouseffect is low. In addition, when it is 5 at % or more, advantageouseffect is low. In the case where an amount of additive elements is 0.05at % or less, in particular, performance of forming a passive coat andpreventing corrosion is lowered. Conversely, in the case where an amountof additive elements is 5 at % or more, the lowering of the reflectivityand thermal characteristics becomes substantial. The above-describedamount of additive elements denotes an amount analyzed by forming areflection film simplex on a substrate on which no reaction occurs or asubstrate composed of elements separated by analysis even if a reactionoccurs. Therefore, in the storage medium, the additive elements movefrom the inside of the reflection film onto an interface of an organicdye material and the like, thereby forming a passive coat, and thus,locally different portions may exist. Therefore, an amount of additiveelements indicates a value obtained by analyzing an amount added to thereflection layer without forming a passive coat. With respect to theconcentration of the additive elements in the reflection layer, theadditive elements occasionally move onto an interface with an oppositeadhesive layer in addition to moving onto the interface with the organicdye recording material which is a recording layer, thereby forming apassive coat. To which interface a larger amount of the elements movedepends on type of organic dye recording material to be used, Ag alloyof reflection layer to be used and type of adhesive to be used.

6-2) Description relating to pre-pit shape in coating type organic dyerecording film and on light reflection layer interface

In an H format according to the present embodiment, as shown in FIGS.35A, 35B and 35C, the system lead-in area SYLDI is provided. In thisarea, an emboss pit area 211 is provided, and, as shown in FIGS. 71A and71B, information is recorded in advance in the form of a pre-bit. Areproduction signal in this area is adjusted to conform to reproductionsignal characteristics from a read-only type information storage medium,and a signal processor circuit in an information reproducing apparatusor an information recording/reproducing apparatus shown in FIG. 11 iscompatible with a read-only type information storage medium and awrite-once type information storage medium. A definition relevant to asignal detected from this area is adjusted to conform with a definitionof “3-4): Description of characteristics relating to “H-L” recordingfilm in the invention”. That is, a reproduction signal amount from thespace area 14 having a sufficiently large length (11 T) is defined asI_(11H) and a reproduction signal from the pre-pit (emboss) area 13having a sufficiently large length (11 T) is defined as I_(11L). Inaddition, a differential value between these amounts is defined asI₁₁=I_(11H)−I_(11L). In the present embodiment, in accordance with thereproduction signal characteristics from the read-only type informationstorage medium, the reproduction signal in this area is set to be:I ₁₁ /I _(11H)≧0.3  (54)and desirably, is set to be:I ₁₁ /I _(11H)>0.5  (55)

When a repetitive signal amplitude of the space area 14 relevant to thepre-pit (emboss) area 13 having a 2 t length is defined as I₂, theamplitude is set to be:I ₂ /I ₁₁≧0.5  (56)and desirably, is set to be:I ₂ /I ₁₁>0.7  (57)

A description will be given with respect to a physical condition formeeting the above formula (54) or formula (55).

As has been described in FIG. 2B, the signal characteristics from apre-pit are mainly dependent on the reflection in the light reflectionlayer 4-2. Therefore, the reproduction signal amplitude value I₁₁ isdetermined depending on a step amount Hpr between the space area 14 andthe pre-pit (emboss) area 13 in the light reflection layer 4-2. Whenoptical approximation calculation is made, this step amount Hpr, withrespect to a reproduction light wavelength λ and a refractive index n₃₂in the recording layer 3-2, has the following relationship:I ₁₁∝ sin²{(2π×Hpr×n ₃₂)/λ}  (58)

From formula (58), it is found that I₁₁ becomes maximal when Hpr≈λ/(4×n₃₂). In order to meet formula (54) or formula (55), from formula (58),it is necessary to meet:Hpr≧λ/(12×n ₃₂)  (59)and desirably,Hpr>λ/(6×n ₃₂)  (60)

As described in “Chapter 0: Description of Relationship between UseWavelength and the Present Embodiment”, λ=355 nm to 455 nm is used inthe embodiment, and as described in “2-1) Difference in Principle ofRecording/Recording Film and Difference in Basic Concept Relating toGeneration of Reproduction Signal”, n₃₂=1.4 to 1.9 is established. Thus,when this value is substituted into formula (59) or formula (60), a stepis produced so as to meet a condition:Hpr≧15.6 nm  (62)and desirably,Hpr>31.1 nm  (63)

In the conventional write-once type information storage medium, as shownin FIG. 71B, the thickness of the recording layer 3-2 is small in thespace area 14, and thus, a step on an interface between the lightreflection layer 4-2 and the recording layer 3-2 is small, and formula(62) has not successfully met. In contrast, in the present embodiment, acontrivance has been made to ensure that a relationship between thethickness Dg of the recording layer 3-2 in the pre-pit (emboss) area 13and the thickness Dl of the recording layer 3-2 in the space area 14conform with a condition described in “3-2-E] Basic characteristicsrelating to thickness distribution of recording layer in the presentembodiment for definition of parameters”. As a result, as shown in FIG.71B, a sufficiently large step Hpr which meets formula (62) or formula(63) has been successfully provided.

By carrying out optical approximation discussion as described above, inthe present embodiment, in order to have sufficient resolution of areproduction signal so as to meet formula (56) or formula (57), acontrivance is made so that the width Wp of the pre-pit (emboss) area 13is equal to or smaller than half of track pitches as shown in FIG. 71B,and a reproduction signal from the pre-pit (emboss) area 13 can belargely taken.

6-3) Description relating to pre-groove shape in coating type organicdye recording film and on light reflection layer interface:

Chapter 7: Description of H Format

Now, an H format in the present embodiment will be described here.

FIG. 31 shows a structure and dimensions of an information storagemedium in the present embodiment. As embodiments, there are explicitlyshown three types of embodiments of information storage mediums such as:

“read-only type information storage medium” used exclusively forreproduction in which recording cannot be carried out;

“write-once type information storage medium” capable of additionalrecording; and

“rewritable type information storage medium” capable of rewriting orrecording any times

As shown in FIG. 31, the above three types of information storagemediums are common to each other in a majority of structure anddimensions. In all of the three types of information storage mediums,from their inner periphery side, a burst cutting area BCA, a systemlead-in area SYLDI, a connection area CNA, a data lead-in area DTLSI,and a data area DTA have been arranged. All the mediums other than anOPT type read-only medium is featured in that a data lead-out area DTLDOis arranged at the outer periphery. As described later, in the OPT typeread-only medium, a middle area MDA is arranged at the outer periphery.In either of the write-once type and rewritable type mediums, the insideof this area is for read-only (additional writing disabled). In theread-only type information storage medium, information is recorded inthe data lead-in area DTLDI in the form of emboss (pre-pit). Incontrast, in the write-once type and the rewritable type informationstorage medium, new information can be additionally written (rewrittenin the rewritable type) by forming a recording mark in the data lead-inarea DTLDI. As described later, in the write-once type and rewritabletype information storage medium, in the data lead-out area DTLDO, therecoexist an area in which additional writing can be carried out(rewriting can be carried out in the rewritable type) and a read-onlyarea in which information is recorded in the form of emboss (pre-pit).As described previously, in the data area DTA, data lead-in area DTLVI,data lead-out area DTSDO, and middle area MDA shown in FIG. 31, highdensity of the information storage medium is achieved (in particular,line density is improved) by using a PRML (Partial Response MaximumLikelihood) method for reproduction of signals recorded therein. Inaddition, in the system lead-in area SYLDI and the system lead-out areaSYLDO, compatibility with a current DVD is realized and the stability ofreproduction is improved by using a slice level detecting system forreproduction of signals recorded therein.

Unlike the current DVD specification, in the embodiment shown in FIG.31, the burst cutting area BCA and system lead-in area SYLDI areseparated from each other in location without being superimposed on eachother. These areas are physically separated from each other, therebymaking it possible to prevent interference between the informationrecorded in the system lead-in area SYLDI at the time of informationreproduction and the information recorded in the burst cutting area BCAand to allocate information reproduction with high precision.

In the case where an “L-H” type recording film has been used as anotherembodiment, there is a method for forming fine irregularities in advancein location for allocating the burst cutting area BCA. A descriptionwill be given later with respect to information on polarity(identification of “H-L” or “L-H”) of a recording mark which exists at a192nd byte in FIG. 42. In this section, a description will be given withrespect to the present embodiment in which an “L-H” recording film aswell as the “H-L” recording film is also incorporated in a specificationand a scope of selecting the recording film is widened to enable highspeed recording or supply of an inexpensive medium. As described later,the present embodiment also considers a case of using the “L-H”recording film. Data recorded in the burst cutting area BCA (barcodedata) is formed by locally carrying out laser exposure to a recordingfilm. As shown in FIGS. 35A, 35B and 35C, the system lead-in area SYLDIis formed of the emboss bit area 211, and thus, the reproduction signalfrom the system lead-in area SYLDI appears in a direction in which alight reflection amount decreases as compared with a light reflectionlevel from the mirror surface 210. If while the burst cutting area BCAis formed as the mirror surface 210, in the case where the “L-H”recording film has been used, a reproduction signal from the datarecorded in the burst cutting area BCA appears in a direction in which alight reflection amount increases more significantly than a lightreflection level from the mirror surface 210 (in an unrecorded state).As a result, a significant step occurs between a position (amplitudelevel) of a maximum level and a minimum level of the reproduction signalfrom the data recorded in the burst cutting area BCA and a position(amplitude level) of a maximum level and a minimum level of thereproduction signal from the system lead-in area SYLDI. As describedlater with respect to FIGS. 35A, 35B and 35C, an information reproducingapparatus or an information recording/reproducing apparatus carry outprocessing in accordance with the steps of:

1) reproducing information in the burst cutting area BCA;

2) reproducing information contained in a information data zone CDZ inthe system lead-in area SYLDI;

3) reproducing information contained in the data lead-in area DTLDI (inthe case of write-once type or rewriting type);

4) readjusting (optimizing) a reproduction circuit constant in areference code recording zone RCZ; and

5) reproducing information recorded in the data area DTA or recordingnew information.

Thus, if there exists a large step between a reproduction signalamplitude level from the data formed in the burst cutting area BCA and areproduction signal amplitude level from the system lead-in area SYLDI,there occurs a problem that the reliability of information reproductionis lowered. In order to solve this problem, in the case where the “L-H”recording film is used as a recording film, the present embodiment isfeatured in that fine irregularities are formed in advance in thus burstcutting area BCA. When such fine irregularities are formed, the lightreflection level becomes lower than that from the mirror surface 210 dueto a light interference effect at the stage prior to recording data(barcode data) by local laser exposure. Then, there is attained anadvantageous effect that a step is remarkably decreased between areproduction signal amplitude level (detection level) from the dataformed in the burst cutting area BCA and a reproduction signal amplitudelevel (detection level) from the system lead-in area SYLDI; thereliability of information reproduction is improved; and processinggoing from the above item 1) to item 2) is facilitated. In the case ofusing the “L-H” recording film, the specific contents of fineirregularities formed in advance in the burst cutting area BCA includethe emboss pit area 211 like the system lead-in area SYLDI. Anotherembodiment includes a method for forming the groove area 214 or the landarea and the groove area 213 like the data lead-in area DTLDI or dataarea DTA. As has been described in the description of embodiments inwhich the system lead-in area SYSDI and burst cutting area BCA areseparately arranged, if the burst cutting area BCA and the emboss bitarea 211 overlaps each other, there increases a noise component from thedata provided in the burst cutting area BCA due to unnecessaryinterference to a reproduction signal. When the groove area 214 or theland area and groove area 213 is formed without forming the emboss pitarea 211 as an embodiment of the fine irregularities in the burstcutting area BCA, there is attained an advantageous effect that theredecreases a noise component from the data formed in the burst cuttingarea BCA due to unnecessary interference to a reproduction signal andthe quality of a reproduction signal is improved. When track pitches ofthe groove area 214 or the land area and groove area 213 formed in theburst cutting area BCA are adjusted to conform with the those of thesystem lead-in area SYLDI, there is attained an advantageous effect thatthe manufacturing performance of the information storage medium isimproved. That is, at the time of original master manufacturing of theinformation storage medium, emboss pits in the system lead-in area areproduced while a feed motor speed is made constant. At this time, thetrack pitches of the groove area 214 or the land area and groove area213 formed in the burst cutting area BCA are adjusted to conform withthose of the emboss pits in the system lead-in area SYLDI, therebymaking it possible to continuously maintain a constant motor speed inthe burst cutting area BCA and the system lead-in area SYLDI. Thus,there is no need for changing the speed of the feed motor midway, andthus, the pitch non-uniformity hardly occurs, and the manufacturingperformance of the information storage (medium is improved.

FIG. 32 shows parameter values according to the present embodiment in aread-only type information storage medium; FIG. 33 shows parametervalues according to the present embodiment in a write-once typeinformation storage medium; and FIG. 34 shows parameter values accordingto the present embodiment in a rewritable type information storagemedium. As is evident in comparison between FIG. 32 or 33 and FIG. 34(in particular, in comparison of section (B)), the rewritable typeinformation storage medium has higher recording capacity than theread-only type or write-once type information storage medium bynarrowing track pitches and line density (data bit length). As describedlater, in the rewritable type information storage medium, the trackpitches are narrowed by reducing effect of a cross-talk of the adjacenttracks by employing land-groove recording. Alternatively, any of theread-only type information storage medium, write-once informationstorage medium, and rewritable-type information storage medium isfeatured in that the data bit length and track pitches (corresponding torecording density) of the system lead-in/system lead-out areasSYLDI/SYLDO are greater than those of the data lead-in/data lead-outarea DTLDI/DTLDO (in that the recording density is low). The data bitlength and track pitches of the system lead-in/system lead-out areasSYLDI/SYLDO are close to the values of the current DVD lead-in area,thereby realizing compatibility with the current DVD. In the presentembodiment as well, like the current DVD-R, an emboss step in the systemlead-in/system lead-out areas SYLDI/SYLDO of the write-once typeinformation storage medium is shallowly defined. In this manner, thereis attained advantageous effect that a depth of a pre-groove of thewrite-once information storage medium is shallowly defined and a degreeof modulation of a reproduction signal from a recording mark formed on apre-groove by additional writing is increased. In contrast, as acounteraction against it, there occurs a problem that the degree ofmodulation of the reproduction signal from the system lead-in/systemlead-out areas SYLDI/SYLDO decreases. In order to solve this problem,the data bit length (and track pitches) of system lead-in/systemlead-out areas SYLDI/SYLDO are roughened and a repetition frequency ofpits and spaces at the narrowest position is isolated (significantlyreduced) from an optical shutdown frequency of an MTF (ModulationTransfer Function) of a reproduction objective lens, thereby making itpossible to increase the reproduction signal amplitude from the systemlead-in/system lead-out areas SYLDI/SYLDO and to stabilize reproduction.

FIGS. 35A, 35B and 35C show a comparison of detailed data structure in asystem lead-in area SYLDI and a data lead-in area DTLDI in a variety ofinformation storage mediums. FIG. 35A shows a data structure of aread-only type information storage medium; FIG. 35B shows a datastructure of a rewritable-type information storage medium; and FIG. 35Cshows a data structure of a write-once type information storage medium.

As shown in FIG. 35A, except that only a connection zone CNZ is formedas a mirror surface 210, the read-only type information storage mediumis featured in that the emboss pit area 211 having emboss pits formedtherein is provided in all of the system lead-in area SYLDI and datalead-in area DTLDI and data area DTA. The emboss pit area 211 isprovided in the system lead-in area SYLDI, and the connection zone CNZis provided in the mirror surface 210. As shown in FIG. 35B, therewritable-type information storage medium is featured in that the landarea and the groove area 213 are formed in the data lead-in area DTLSIand the data area DTA. The write-once type information storage medium isfeatured in that the groove area 214 is formed in the data lead-in areaDTLDI and the data area DTA. Information is recorded by forming arecording mark in the land area and the groove area 213 or groove area214.

The initial zone INZ indicates a start position of the system lead-inarea SYLDI. As significant information recorded in the initial zone INZ,there is discretely arranged data ID (Identification Data) informationincluding information on physical sector numbers or logical sectornumbers described previously. As described later, one physical sectorrecords information on a data frame structure composed of data ID, IED(ID Error Detection code), main data for recording user information, andEDC (Error detection code); and the initial zone records information onthe above described data frame structure. However, in the initial zoneINZ, all the information on the main data for recording the userinformation is all set to “00h”, and thus, the significant informationcontained in the initial zone INZ is only data ID information. A currentlocation can be recognized from the information on physical sectornumbers or logical sector numbers recorded therein. That is, when aninformation recording/reproducing unit 141 shown in FIG. 11 startsinformation reproduction from an information storage medium, in the casewhere reproduction has been started from the information contained inthe initial zone INZ, first, the information on physical sector numbersor logical sector numbers recorded in the data ID information issampled, and the sampled information is moved to the control data zoneCDZ while the current location in the information storage medium ischecked.

A buffer zone 1 BFZ1 and a buffer zone 2 BFZ2 each are composed of 32ECC blocks. As shown in FIGS. 32, 33 and 34, one ECC block correspondsto 1024 physical sectors. In the buffer zone 1 BFZ1 and the buffer zone2 BFZ2 as well, like the initial zone INZ, main data information is setto all “00h”.

The connection zone CNZ which exists in a CNA (Connection Area) is anarea for physically separating the system lead-in area SYLDI and thedata lead-in area DTLDI from each other. This area is provided as amirror surface on which no emboss pit or pre-groove exists.

An RCZ (Reference code zone) of the read-only type information storagemedium and the write-once type information storage medium each is anarea used for reproduction circuit tuning of a reproducing apparatus(for automatic adjustment of tap coefficient values at the time ofadaptive equalization carried out in the tap controller 332 shown inFIG. 15), wherein information on the data frame structure describedpreviously is recorded. A length of the reference code is one ECC block(=32 sectors). The present embodiment is featured in that the RCZ(Reference code zone) of the read-only type information storage mediumand the write-once information storage medium each is arranged adjacentto a DTA (data area). In any of the structures of the current DVD-ROMdisk and the current DVD-R disk as well, a control data zone is arrangedbetween the reference code zone and data area, and the reference codezone and the data area are separated from each other. If the referencecode zone and data area are separated from each other, a tilt amount ora light reflection factor of the information storage medium or therecording sensitivity of a recording film (in the case of the write-onceinformation storage medium) slightly changes. Therefore, there occurs aproblem that an optimal circuit constant in the data area is distortedeven if a circuit constant of the reproducing apparatus is adjusted. Inorder to solve the above described problem, when the RCZ (reference codezone) is arranged adjacent to the DTA (data area), in the case where thecircuit constant of the information reproducing apparatus has beenoptimized in the RCZ (reference code zone), an optimized state ismaintained by the same circuit constant in the DTA (data area). In thecase where an attempt is made to precisely reproduce a signal inarbitrary location in the DTA (data area), it becomes possible toreproduce a signal at a target position very precisely in accordancewith the steps of:

1) optimizing a circuit constant of the information reproducingapparatus in the RCZ (reference code zone);

2) optimizing a circuit constant of the information reproducingapparatus again while reproducing a portion which is the closest to thereference code zone RCZ in the data area DTA;

3) optimizing a circuit constant once again while reproducinginformation at an intermediate position between a target position in thedata area DTA and the position optimized in step 2); and

4) reproducing signal after moving to the target position.

GTZ1 and GTZ2 (guard track zones 1 and 2) existing in the write-onceinformation storage medium and the rewritable-type information storagemedium are areas for specifying the start boundary position of the datalead-in area DTLDI, and a boundary position of a drive test zone DRTZand a disc test zone DKTZ. These areas are prohibited from beingrecorded a recording mark. The guard track zone 1 GTZ1 and guard trackzone 2 GTZ2 exist in the data lead-in area DTLDI, and thus, in thisarea, the write-once type information storage medium is featured in thatthe pre-groove area is formed in advance. Alternatively, therewritable-type information storage medium is featured in that thegroove area and the land area are formed in advance. In the pre-groovearea or groove area and the land area, as shown in FIGS. 32, 33 and 34,wobble addresses are recorded in advance, and thus, the current locationin the information storage medium is determined by using these wobbleaddresses.

The disk test zone DKTZ is an area provided for manufactures ofinformation storage mediums to carry out quality test (evaluation).

The drive test zone DRTZ is provided as an area for carrying out testwriting before the information recording/reproducing apparatus recordsinformation in the information storage medium. The informationrecording/reproducing apparatus carries out test writing in advance inthis area, and identifies an optimal recording condition (writestrategy). Then, the information contained in the data area DTA can berecorded under the optimal recording condition.

The information recorded in the disk identification zone DIZ whichexists in the rewritable-type information storage medium (FIG. 35B) isan optional information recording area, the area being adopted toadditionally write a set of drive descriptions composed of: informationon manufacturer name of recording/reproducing apparatuses; additionalinformation relating thereto; and an area in which recording can beuniquely carried out by the manufacturers.

A defect management area 1 DMA1 and a defect management area 2 DMA2which exist in a rewritable-type information storage medium (FIG. 35B)record defect management information contained in the data area DTA,and, for example, substitute site information when a defect occurs orthe like is recorded.

In the write-once type information storage medium (FIG. 35C), thereexist uniquely: an RMD duplication zone RDZ; a recording management zoneRMZ; and an R physical information zone R-PFIZ. The recording managementzone RMZ records RMD (recording management data) which is an item ofmanagement information relating to a recording position of data updatedby additional writing of data. A detailed description will be givenlater. As described later in FIGS. 36 (a), (b), (c) and (d), in thepresent embodiment, a recording management zone RMZ is set for eachbordered area BRDA, enabling area expansion of the recording managementzone RMZ. As a result, even if the required recording management dataRMD increases due to an increase of additional writing frequency, suchan increase can be handled by expanding the recording management zoneRMZ in series, and thus, there is attained advantageous effect that theadditional writing count can be significantly increased. In this case,in the present embodiment, the recording management zone RMZ is arrangedin a border-in BRDI which corresponds to each bordered area BRDA(arranged immediately before each bordered area BRDA). In the presentembodiment, the border-in BRDI corresponding to the first bordered areaBRDA#1 and a data lead-in area DTLDI are made compatible with eachother, and efficient use of the data area DTA is promoted while theforming of the first border-in BRDI in the data area DTA is eliminated.That is, the recording management zone RMZ in the data lead-in area DTAshown in FIG. 35C is utilized as a recording location of the recordingmanagement data RDM which corresponds to the first bordered area BRDA#1.

The RMD duplication zone RDZ is a location for recording information onthe recording management data RMD which meets the following condition inthe recording management zone RMZ, and the reliability of the recordingmanagement data RMD is improved by providing the recording managementdata RMD in a duplicate manner, as in the present embodiment. That is,in the case where the recording management data RMD contained in therecording management zone RMZ is valid due to dust or scratch adheringto a write-once information storage medium surface, the recordingmanagement data RMD is reproduced, the data being recorded in this RMDduplication zone RDZ. Further, the remaining required information isacquired by tracing, whereby information on the latest recordingmanagement data RMD can be restored.

This RMD duplication zone records recording management data RDM at atime point at which (a plurality of) borders are closed. As describedlater, a new recording management zone RMZ is defined every time oneborder is closed and a next new bordered area is set. Thus, every time anew recording management zone RMZ is created, the last recordingmanagement data RMD relating to the preceding bordered area may berecorded in this RMD duplication zone RDZ. When the same information isrecorded in this RMD duplication zone RDZ every time the recordingmanagement data RDM is additionally recorded on a write-once informationstorage medium, the RMD duplication zone RDZ becomes full with acomparatively small additional recording count, and thus, an upper limitvalue of the additional writing count becomes small. In contrast, as inthe present embodiment, in the case where a recording management zone isnewly produced when a border is closed, the recording management zone inthe border-in BRDI becomes full, and a new recording management zone RMZis formed by using an R zone, there is attained advantageous effect thatonly the last recording management data RMD contained in the pastrecording management zone RMZ is recorded in the RMD duplication zoneRDZ, thereby making it possible to improve an allowable additionalwriting count by efficiently using the RMD duplication zone RDZ.

For example, in the case where the recording management data RMDcontained in the recording management zone RMZ which corresponds to thebordered area BRDA on the way of additional writing (before closed)cannot be reproduced due to the dust or scratch adhering to the surfaceof the write-once type information storage medium, a location of thebordered area BRDA, which has been already closed, can be identified byreading the recording management data RMD lastly recorded in this RMDduplication zone RDZ. Therefore, the location of the bordered area BRDAon the way of additional writing (before closed) and the contents ofinformation recorded therein can be acquired by tracing another locationin the data area DTA of the information storage medium, and theinformation on the latest recording management data RMD can be restored.

An R physical information zone R-PFIZ records the information analogousto the physical format PFI contained in the control data zone CDZ whichexists common to FIGS. 35A to 35C (described later in detail).

FIG. 36 shows a data structure in the RMD duplication zone RDZ and therecording management zone RMZ which exists in the write-once typeinformation storage medium (FIG. 35C). FIG. 36 (a) shows the samestructure as that shown in FIG. 35C, and FIG. 36 (b) shows an enlargedview of the RMD duplication zone RDZ and the recording management zoneRDZ shown in FIG. 35C. As described above, in the recording managementzone RMZ contained in the data lead-in area DTLDI, data relating torecording management which corresponds to the first bordered area BRDAis collectively recorded, respectively, in one items of recordingmanagement data (RMD); and new recording management data RMD issequentially additionally written at the back side every time thecontents of the recording management data RMD generated when additionalwriting process has been carried out in the write-once informationstorage medium are updated. That is, the RMD (Recording Management Data)is recorded in size units of single physical segment block (a physicalsegment block will be described later), and new recording managementdata RMD is sequentially additionally written every time the contents ofdata are updated. In the example shown in FIG. 36 (b), a change hasoccurred with management data in location recording management dataRMD#1 and RMD#2 has been recorded. Thus, this figure shows an example inwhich the data after changed (after updated) has been recorded asrecording management data RMD#3 immediately after the recordingmanagement data RMD#2. Therefore, in the recording management zone RMD,a reserved area 273 exists so that additional writing can be furthercarried out.

Although FIG. 36 (b) shows a structure in the recording management zoneRMZ which exists in the data lead-in area DTLDI, a structure in therecording management zone RMZ (or expanded recording management zone:referred to as expanded RMZ) which exists in the border-in BRDI orbordered area BRDA described later is also identical to the structureshown in FIG. 36 (b) without being limited thereto.

In the present embodiment, in the case where a first bordered areaBRDA#1 is closed or in the case where the terminating process(finalizing) of the data area DTA is carried out, a processing operationfor padding all the reserved area 273 shown in FIG. 36 (b) with thelatest recording management data RMD duplication zone is carried out. Inthis manner, the following advantageous effects are attained:

1) An “unrecorded” reserved area 273 is eliminated, and thestabilization of tracking correction due to a DPD (Differential PhaseDetection) technique is guaranteed;

2) the latest recording management data RMD is overwritten in the pastreserved area 273, thereby remarkably improving the reliability at thetime of reproduction relating to the last recording management data RMD;and

3) an event that different items of recording management data RMD aremistakenly recorded in an unrecorded reserved area 273 can be prevented.

The above processing method is not limited to the recording managementzone RMZ contained in the data lead-in area DTLDI. In the presentembodiment, with respect to the recording management zone RMZ (orexpanded recording management zone: referred to as expanded RMZ) whichexists in the border-in BRDI or bordered area BRDA described later, inthe case where the corresponding bordered area BRDA is closed or in thecase where the terminating process (finalizing) of the data area DTA iscarried out, a processing operation for padding all the reserved area273 shown in FIG. 36 (b) with the latest recording management data RMDis carried out.

The RMD duplication zone RDZ is divided into the RDZ lead-in area RDZLIand a recording area 271 of the last recording management data RMDduplication zone RDZ of the corresponding RMZ. The RDZ lead-in areaRDZLI is composed of a system reserved field SRSF whose data size is 48KB and a unique ID field UIDF whose data size is 16 KB, as shown in FIG.36 (b). All “00h” are set in the system reserved field SRSF.

The present embodiment is featured in that DRZ lead-in area RDZLI isrecorded in the data lead-in area DTLDI which can be additionallywritten. In the write-once type information storage medium according tothe present embodiment, the medium is shipped with the RDZ lead-in areaRDZLI being in an unrecorded state immediately after manufacturing. Inthe user's information recording/reproducing apparatus, at a stage ofusing this write-once type information storage medium, RDZ lead-in areaRDZLI information is recorded. Therefore, it is determined whether ornot information is recorded in this RDZ lead-in area RDZLI immediatelyafter the write-once type information storage medium has been mounted onthe information recording/reproducing apparatus, thereby making itpossible to easily know whether or not the target write-once typeinformation storage medium is in a state immediately aftermanufacturing/shipment or has been used at least once. Further, as shownin FIG. 36, the present embodiment is secondarily featured in that theRMD duplication zone RDZ is provided at the inner periphery side thanthe recording management zone RMZ which corresponds to a first borderedarea BRDA, and the RDZ lead-in RDZLI is arranged in the RMD duplicationzone RDZ.

The use efficiency of information acquisition is improved by arranginginformation (RDZ lead-in area RDZLI) representing whether or not thewrite-once type information storage medium is in a state immediatelyafter manufacturing/shipment or has been used at least once in the RMDduplication zone RDZ used for the purpose of a common use (improvementof reliability of RMD). In addition, the RDZ lead-in area RDZLI isarranged at the inner periphery side than the recording management zoneRMZ, thereby making it possible to reduce a time required foracquisition of required information. When the information storage mediumis mounted on the information recording/reproducing apparatus, theinformation recording/reproducing apparatus starts reproduction from theburst cutting area BCA arranged at the innermost periphery side, asdescribed in FIG. 31, and sequentially changes a reproducing locationfrom the system lead-in SYLSI to the data lead-in area DTLDI while thereproduction position is sequentially moved to the innermost peripheryside. It is determined whether or not information has been recorded inthe RDZ lead-in area RDZLI contained in the RMD duplication zone RDZ. Ina write-once type information storage medium in which no recording iscarried out immediately after shipment, no recording management data RMDis recorded in the recording management zone RMZ. Thus, in the casewhere no information is recorded in the RDZ lead-in area RDZLI, it isdetermined that the medium is “unused immediately after shipment”, andthe reproduction of the recording management zone RMD can be eliminated,and a time required for acquisition of required information can bereduced.

As shown in FIG. 36 (c), a unique ID area UIDF records informationrelating to an information recording/reproducing apparatus for which thewrite-once type information storage medium immediately after shipmenthas been first used (i.e., for which recording has been first started).That is, this area records a drive manufacturer ID 281 of theinformation recording/reproducing apparatus or serial number 283 andmodel number 284 of the information recording/reproducing apparatus. Theunique ID area UIDF repeatedly records the same information for 2 KB(strictly, 2048 bytes) shown in FIG. 36 (c). Information contained inthe unique disk ID 287 records year information 293, month information294, date information 295, time information 296, minutes information297, and seconds information 298 when the storage medium has been firstused (recording has been first started). A data type of respective itemsof information is described in HEX, BIN, ASCII as described in FIG. 36(d), and two types or four bytes are used.

The present embodiment is featured in that the size of an area of thisRDZ lead-in area RDZLI and the size of the one recording management dataRMD are 64 KB, i.e., the user data size in one ECC block becomes aninteger multiple. In the case of the write-once type information storagemedium, it is impossible to carry out a processing operation forrewriting ECC block data after changed in the information storage mediumafter changing part of the data contained in one ECC block. Therefore,in particular, in the case of the write-once type information storagemedium, as described later, data is recorded in recording cluster unitscomposed of an integer multiple of a data segment including one ECCblock. Therefore, the size of the area of the RDZ lead-in area RDZLI andthe size of such one item of recording management data RMD are differentfrom a user data size in an ECC block, there is a need for a paddingarea or a stuffing area for making adjustment to the recording clusterunit, and a substantial recording efficiency is lowered. As in thepresent embodiment, the size of the area of the RDZ lead-in area RDZLIand the size of such one item of recording management data RMD are setto an integer multiple of 64 KB, thereby making it possible to lower therecording efficiency.

A description will be given with respect to a last recording managementdata RMD recording area 271 of the corresponding RMZ shown in FIG. 36(b). As described in Japanese Patent No. 2621459, there is a method forrecording intermediate information at the time of interruption ofrecording inwardly of the lead-in area. In this case, every timerecording is interrupted or every time an additional writing process iscarried out, it is necessary to serially additionally write intermediateinformation in this area (recording management data RMD in the presentembodiment). Thus, if such recording interruption or additional writingprocess is frequently repeated, there is a problem that this areabecomes full immediately and a further adding process cannot be carriedout. In order to solve this problem, the present embodiment is featuredin that an RMD duplication zone RDZ is set as an area capable ofrecording the recording management data RMD updated only when a specificcondition is met and the recording management data RMD sampled undersuch a specific condition is recorded. Thus, there is attainedadvantageous effect that the RMD duplication zone RDZ can be preventedfrom being full and the numbers of additional writings enable withrespect to the write-once type information storage medium can beremarkably improved by lowering the frequency of the recordingmanagement data RMD additionally written in the RMD duplication zoneRDZ. In parallel to this effect, the recording management data updatedevery time an additional writing process is carried out is seriallyadditionally written in the recording management zone RMZ in theborder-in area BRDI shown in FIG. 36 (a) (in the data lead-in area DTLDIas shown in FIG. 36 (a) with respect to the first bordered area BRDA#1)or the recording management zone RMZ utilizing an R zone describedlater. When a new recording management zone RMZ is created, for example,when the next bordered area BRDA is created (new border-in area BRDI isset) or when a new recording management zone RMZ is set in an R zone,the last recording management data RMD (the newest RMD in a stateimmediately before creating a new recording management zone RMZ) isrecorded in (the corresponding last recording management data RMDrecording area 271) contained in the RMD duplication zone RDZ. In thismanner, there is attained advantageous effect that a newest RMD positionsearch is facilitated by utilizing this area in addition to asignificantly increase of additional writing enable count for thewrite-once type information storage medium.

FIG. 38 shows a data structure in the recording management data RMDshown in FIG. 36. FIG. 38 shows the same contents of FIG. 36. Asdescribed previously, in the present embodiment, the border-in area BRDIfor the first bordered area BRDA#1 is partially compatible with the datalead-in area DTLDI, and thus, the recording management data RMD#1 to #3corresponding to the first bordered area are recorded in the recordingmanagement zone RMZ in the data lead-in area DTLDI. In the case where nodata is recorded in the data area DTA, the inside recording managementzone RMZ is provided as a reserved area 273 in which all data is in anunrecorded state. The recording management data RMD updated every timedata is additionally written in the data area DTA is recorded in firstlocation contained in this reserved area 273, and the correspondingrecording management data RMD is sequentially additionally written inthe first bordered area contained in the recording management zone RMZ.The size of the recording management data RMD additionally written eachtime in the recording management zone RMZ is defined as 64 KB. In thepresent embodiment, one ECC block is composed of 64 KB data, and thus,an additional writing process is simplified by adjusting the data sizeof this recording management data RMD to conform with one ECC blocksize. As described later, in the present embodiment, one data segment490 is configured by adding part of a guard area before and after oneECC block data 412, and recording clusters 540 and 542 in units ofadditional writing or rewriting are configured by adding expanded guardfields 258 and 259 to one or more (n) data segments. In the case ofrecording the recording management data RMD, the recording clusters 540and 542 including only one data segment (one ECC block) are sequentiallyadditionally written in this recording management zone RMZ. As describedlater, a length of a location for recording one data segment 531corresponds to that of one physical segment block composed of sevenphysical segments 550 to 556.

FIG. 38 (c) shows a data structure in one recording management dataRMF#1. FIG. 38 (c) shows a data structure in recording management dataRMD#1 contained in the data lead-in area DTLDI. The illustrated datastructure is identical to a data structure in the recording managementdata RMD#A and #B (FIG. 36 (b)) recorded in the RMD duplication zoneRDZ; (expanded) recording management data RMD recorded in a border-inarea BRDI described later; (expanded) recording management data RMDrecorded in an R zone; and copy CRMD of RMD recorded in the border-outarea BRDO (FIG. 39 (d)) as well. As shown in FIG. 38 (c), one item ofrecording management data RMD is composed of a reserved area and RMDfields ranging from “0” to “21”. In the present embodiment, 32 physicalsectors are included in one ECC block composed of 64 KB user data, anduser data of 2 KB (strictly, 2048 bytes) is recorded in one physicalsector. Each RMD field are assigned by 2048 bytes in conformance to auser data size recorded in this physical sector, and relative physicalsector numbers are set. RMD fields are recorded on a write-once typeinformation storage medium in order of these relative physical sectornumbers. The contents of data recorded in each RMD field are as follows:

RMD field 0 . . . Information relating to disk state and data areaallocation (information relating to location for allocating a variety ofdata in data area)

RMD field 1 . . . Information relating to used test zone and informationrelating to recommended recording waveform

RMD field 2 . . . User available area

RMD field 3 . . . Start position information on border area andinformation relating to expanded RMZ position

RMD fields 4 to 21 . . . Information relating to position of R zone

As shown in FIG. 35 in any of the read-only type, write-once type, andrewritable-type information storage medium, the present embodiment isfeatured in that a system lead-in area is arranged at an opposite sideof a data area while a data lead-in area is sandwiched between the twoareas, and further, as shown in FIG. 31, the burst cutting area BCA andthe data lead-in area DTLDI are arranged at an opposite side to eachother while the system lead-in area SYSDI is sandwiched between the twoareas. When an information storage medium is inserted into theinformation reproducing apparatus or information recording/reproducingapparatus shown in FIG. 11, the information reproducing apparatus orinformation recording/reproducing apparatus carries out processing inaccordance with the steps of:

1) reproducing information contained in the burst cutting area BCA;

2) reproducing information contained in the information data zone CDZcontained in the system lead-in area SYLDI;

3) reproducing information contained in the data lead-in area DTLDI (inthe case of a write-once type or a rewritable-type medium);

4) readjusting (optimizing) a reproduction circuit constant in thereference code zone RCZ; and

5) reproducing information recorded in the data area DTA or recordingnew information.

As shown in FIG. 35, information is sequentially arranged from the innerperiphery side along the above processing steps, and thus, a process forproviding an access to an unnecessary inner periphery is eliminated, thenumber of accesses is reduced, and the data area DTA can be accessed.Thus, there is attained advantageous effect that a start time forreproducing the information recording in the data area or recording newinformation is accelerated. In addition, RPML is used for signalreproduction in the data lead-in area DTDLI and data area DTA byutilizing a slice level detecting system for signal reproduction in thesystem lead-in area SYLDI. Thus, if the data lead-in area DTLDI and thedata area DTA are made adjacent to each other, in the case wherereproduction is carried out sequentially from the inner periphery side,a signal can be stably reproduced continuously merely by switching aslice level detecting circuit to a PRML detector circuit only oncebetween the system lead-in area SYLDI and the data lead-in area DTLDI.Thus, the number of reproduction circuit switchings along thereproduction procedures is small, thus simplifying processing controland accelerating a data intra-area reproduction start time.

FIG. 37 shows a comparison of the data structures in the data areas DTAand the data lead-out areas DTLDO in a variety of information storagemediums. FIG. 37( a) shows a data structure of a read-only typeinformation storage medium; FIGS. 37( b) and 37(c) each show a datastructure of a writing-type information storage medium; and FIG. 37( d)to 37(f) each show a data structure of a write-once type informationstorage medium. In particular, FIGS. 37( b) and 37(d) each show a datastructure at the time of an initial state (before recording); and FIGS.37( c), 37(e) and 37(f) each show a data structure in a state in whichrecording (additional writing or rewriting) has advanced to a certainextent.

As shown in FIG. 37( a), in the read-only type information storagemedium, the data recorded in the data lead-out area DTLDO and the systemlead-out area SYLDO each have a data frame structure (described later indetail) in the same manner as in the buffer zone 1 BFZ1 and buffer zone2 BFZ2 shown in FIGS. 35( a) to 35(c), and all values of the main datacontained therein are set to “00h”. In the read-only type informationstorage medium, a user data prerecording area 201 can be fully used inthe data area DTA. However, as described later, in any of theembodiments of the write-once information storage medium andrewritable-type information storage medium as well, userrewriting/additional writing enable ranges 202 to 205 are narrower thanthe data area DTA.

In the write-once information storage medium or rewritable-typeinformation storage medium, an SPA (Spare Area) is provided at theinnermost periphery of the data area DTA. In the case where a defect hasoccurred in the data area DTA, a substituting process is carried out byusing the spare area SPA. In the case of the rewritable-type informationstorage medium, the substitution history information (defect managementinformation) is recorded in a defect management area 1 (DMA1) and adefect management area 2 (DMA2) shown in FIG. 35( b); and a detectmanagement area 3 (DMA3) and a defect management area 4 (DMA4) shown inFIGS. 37( b) and 37(c). The defect management information recorded inthe defect management area 3 (DMA3) and defect management area 4 (DMA4)shown in FIGS. 37( b) and 37(c) are recorded as the same contents of thedefect management information recorded in the defect managementinformation 1 (DMA1) and defect management information 2 (DMA2) shown inFIG. 35B. In the case of the write-once type information storage medium,substitution history information (defect management information) in thecase where the substituting process has been carried out is recorded inthe data lead-in area DTLDI shown in FIG. 35C and copy information C_RMZon the contents of recoding in a recording management zone which existsin a border zone. Although defect management has not been carried out ina current DVD-R disk, DVD-R disks partially having a defect location arecommercially available as the manufacture number of DVD-R disksincreases, and there is a growing need for improving the reliability ofinformation recorded in a write-once type information storage medium. Inthe embodiment shown in FIGS. 37A to 37F, a spare area SPA is set withrespect to the write-once information storage medium, enabling defectmanagement by a substituting process. In this manner, a defectmanagement process is carried out with respect to the write-once typeinformation storage medium partially having a defect location, therebymaking it possible to improve the reliability of information. In therewritable-type information storage medium or write-once typeinformation storage medium, in the case where a defect frequently hasoccurred, a user judges an information recording/reproducing apparatus,and an ESPA, ESPA1, and ESPA2 (Expanded Spare Areas) are automaticallyset with respect to a state immediately after selling to the user shownin FIGS. 37A and 37D so as to widen a substitute location. In thismanner, the expanded spare areas ESPA, ESPA1, and ESPA2 can be set,thereby making it possible to sell mediums with which a plenty ofdefects occur for a manufacturing reason. As a result, the manufactureyield of mediums is improved, making it possible to reduce a medialprice. As shown in FIGS. 37A, 37E and 37F, when the expanded spare areasESPA, ESPA1, and ESPA2 are expanded in the data area DTA, user datarewriting or additional writing enable ranges 203 and 205 decrease(s),thus making it necessary to management its associated positionalinformation. In the rewritable-type information storage medium, theinformation is recorded in the defect management area 1 (DMA1) to thedefect management area 4 (DMA4) and in the control data zone CDZ, asdescribed later. In the case of the write-once type information storagemedium, as described later, the information is recorded in recordingmanagement zones RMZ which exist in the data lead-in area DTLDI and inthe border-out BRDO. As described later, the information is recorded inthe RMD (Recording Management Data) contained in the recordingmanagement zone RMZ. The recording management data RMD is updated oradditionally written in the recoding management zone RMZ every time thecontents of management data are updated. Thus, even if an expanded sparearea is reset many times, timely updating and management can be carriedout. (The embodiment shown in FIG. 37E indicates a state in which anexpanded spare area 2 (ESPA2) has been set because further areasubstituting setting is required due to a number of defects even afterthe expanded spare area 1 (ESPA1) has been fully used).

A guard track zone 3 (GTZ3) shown in FIGS. 37B and 37C each is arrangedto separate a defect management area 4 (DMA4) and a drive test zone(DRTS) from each other, and a guard track zone 4 (GTZ4) is arranged toseparate a disk test zone DKTZ and a servo calibration zone SCZ fromeach other. The guard track zone 3 (GTZ3) and guard track zone 4 (GTZ4)are specified as area which inhibits recording by forming a recordingmark, as in the guard track zone 1 (GTZ1) and guard track zone 2 (GTZ2)shown in FIGS. 35A to 35C. The guard track zone 3 (GTZ3) and the guardtrack zone 4 (GTZ4) exist in the data lead-out area DTLDO. Thus, inthese areas, in the write-once type information storage medium, apre-groove area is formed in advance, or alternatively, in therewritable-type information storage medium, a groove area and a landarea are formed in advance. As shown in FIGS. 32 to 34, wobble addressesare recorded in advance in the pre-groove area or the groove area andland area, thus judging a current position in the information storagemedium by using this wobble addresses.

As in FIGS. 35A to 35C, a drive test zone DRTZ is arranged as an areafor test writing before an information recording/reproducing apparatusrecords information in an information storage medium. The informationrecording/reproducing apparatus carries out test writing in advance inthis area, and identifies an optimal recording condition (writestrategy). Then, this apparatus can record information in the data areaDTA under the optimal recording condition.

As shown in FIGS. 35A to 35C, the disk test zone DKTZ is an areaprovided for manufacturers of information storage mediums to carry outquality test (evaluation).

In all of the areas contained in the data lead-out area DTLDO other thanthe SCZ (Servo Calibration Zone), a pre-groove area is formed in advancein the write-once type information storage medium, or alternatively, agroove area and a land area are formed in advance in the rewritable-typeinformation storage medium, enabling recording (additional writing orrewriting) of a recording mark. As shown in FIGS. 37C and 37E, the SCZ(Servo Calibration Zone) serves as an emboss pit area 211 in the samemanner as in the system lead-in area SYLDI instead of the pre-groovearea 214 or the land area and groove area 213. This area formscontinuous tracks with emboss pits, which follows another area of thedata lead-out area DTLDO. These tracks continuously communicate witheach other in a spiral manner, and form emboss pits over 360 degreesalong the circumference of the information storage medium. This area isprovided to detect a tilt amount of the information storage medium byusing a DPD (Deferential Phase Detect) technique. If the informationstorage medium tilts, an offset occurs with a track shift detectionsignal amplitude using the DPD technique, making it possible toprecisely the tilt amount from the offset amount and a tilting directionin an offset direction. By utilizing this principle, emboss pits capableof DPD detection are formed in advance at the outermost periphery (atthe outer periphery in the data lead-out area DTLDO), thereby making itpossible to carry out detection with inexpensiveness and high precisionwithout adding special parts (for tilt detection) to an optical headwhich exists in the information recording/reproducing unit 141 shown inFIG. 11. Further, by detecting the tilt amount of the outer periphery,servo stabilization (due to tilt amount correction) can be achieved evenin the data area. In the present embodiment, the track pitches in thisservo calibration zone SCZ are adjusted to conform with another areacontained in the data lead-out area DTLD, and the manufacturingperformance of the information storage medium is improved, making itpossible to reduce a media price due to the improvement of yields. Thatis, although a pre-groove is formed in another area contained in thedata lead-out area DTLDO in the write-once type information storagemedium, a pre-groove is created while a feed motor speed of an exposuresection of an original master recording device is made constant at thetime of original master manufacturing of the write-once type informationstorage medium. At this time, the track pitches in the servo calibrationzone SCZ are adjusted to conform with another area contained in the datalead-out area DTLDO, thereby making it possible to continuously maintaina motor speed constantly in the servo calibration zone SCZ as well.Thus, the pitch non-uniformity hardly occurs, and the manufacturingperformance of the information storage medium is improved.

Another embodiment includes a method for adjusting at least either ofthe track pitches and data bit length in the servo calibration zone SCZto conform with the track pitches or data bit length of the systemlead-in area SYLDI. As described previously, the tilt amount in theservo calibration zone SCZ and its tilt direction are measured by usingthe DPD technique, and the measurement result is utilized in the dataarea DTA as well, thereby promoting servo stabilization in the data areaDTA. A method for predicting a tilt amount in the data area DTA isfeatured in that the tilt amount in the system lead-in area SYLDI andits direction are measured in advance by using the DPD techniquesimilarly, and a relationship with the measurement result in the servocalibration zone SCZ is utilized, thereby making it possible to predictthe tilt amount. In the case of using the DPD technique, the presentembodiment is featured in that the offset amount of the detection signalamplitude relevant to a tilt of the information storage medium and adirection in which an offset occurs, change depending on the trackpitches and data bit length of emboss pits. Therefore, there is attainedadvantageous effect that at least either of the track pitches and databit length in the servo calibration zone SCZ is adjusted to conform withthe track pitches or data bit length of the system lead-in area SYLDI,whereby the detection characteristics relating to the offset amount ofthe detection signal amplitude and the direction in which an offsetoccurs are made coincident with each other depending on the servocalibration zone SCZ and the system lead-in area SYLDI; a correlationbetween these characteristics is easily obtained, and the tilt amountand direction in the data area DTA is easily predicted.

As shown in FIGS. 35C and 37D, in the write-once type informationstorage medium, two drive test zones DRTZ are provided at the innerperiphery side and the outer periphery side of the medium. As more testwriting operations are carried out for the drive text zones DRTZ,parameters are finely assigned, thereby making it possible to search anoptimal recording condition in detail and to improve the precision ofrecording in the data area DTA. The rewritable-type information storagemedium enables reuse in the drive test zone DRTZ due to overwriting.However, if an attempt is made to enhance the recording precision byincreasing the number of test writings in the write-once typeinformation storage medium, there occurs a problem that the drive testzone is used up immediately. In order to solve this problem, the presentembodiment is featured in that an EDRTZ (Expanded Drive Test Zone) canbe set from the outer periphery to the inner periphery direction, makingit (possible to expand a drive test zone. In the present embodiment,features relating to a method for setting an expanded drive test zoneand a method for carrying out test writing in the set expanded drivetest zone are described below.

1) The setting (framing) of expanded drive test zones EDRTZ aresequentially provided collectively from the outer periphery direction(close to the data lead-out area DTLDO) to the inner periphery side.

As shown in FIG. 37E, the expanded drive test zone 1 (EDRTZ1) is set asan area collected from a location which is the closest to the outerperiphery in the data area (which is the closest to the data lead-outarea DTLDO); and the expanded drive test zone 1 (EDRTZ1) is used up,thereby making it possible to secondarily set the expanded drive testzone 2 (EDRTZ2) as a corrected area which exists in the inner peripheryside than the current position.

2) Test writing is sequentially carried out from the inner peripheryside in the expanded dive test zone DDRTZ.

In the case where test writing is carried out in the expanded drive testzone EDRTZ, such test writing is carried out along a groove area 214arranged in a spiral shape from the inner periphery side to the outerperiphery side, and current test writing is carried out for anunrecorded location that immediately (follows the previouslytest-written (recorded) location.

The data area is structured to be additionally written along the groovearea 214 arranged in a spiral manner from the inner periphery side tothe outer periphery side. A processing operation from “checkingimmediately test-written location” to “carrying out current testwriting” can be serially carried out by using a method for sequentiallycarrying out additional writing a location that follows a test writinglocation in which test writing in the expanded drive test zone has beencarried out immediately before, thus facilitating a test writing processand simplifying management of the test-written location in the expandeddrive test zone EDRTZ.

3) The data lead-out area DTLDO can be reset in the form including theexpanded drive test zone.

FIG. 37E shows an example of setting two areas, i.e., an expanded sparearea 1 (ESPA1) and an expanded spare area 2 (ESPA2) in the data area DTAand setting two areas, i.e., the expanded drive test zone 1 (EDRTZ1) andexpanded drive test zone 2 (EDRTZ2). In this case, as shown in FIG. 37F,the present embodiment is featured in that the data lead-out area DTLOcan be reset with respect to an area including up to the expanded drivetest zone 2 (EDRTZ2). Concurrently, the range of data area DTA is resetin a range-narrowed manner, making it easy to manage an additionalwriting enable range 205 of the user data which exists in the data areaDTA. In the case where the resetting has been provided as shown in FIG.37F, a setting location of the expanded spare area 1 (ESPA1) shown inFIG. 37E is regarded as an “expanded spare area which has already beenused up”, and an unrecorded area (area enabling additional test writing)is managed only in the expanded spare area 2 (ESPA2) contained in theexpanded drive test zone EDRTZ if any. In this case, non-defectinformation which is recorded in the expanded spare area 1 (ESPA1) andwhich has been used up for substitution is transferred to a location ofan area which is not substituted in the expanded spare area 2 (ESPTA2),and defect management information is rewritten. The start positioninformation on the reset data lead-out area DTLDO is recorded inallocation position information on the latest (updated) data area DTA ofRMD field 0 contained in the recording management data RMD, as shown inFIG. 44.

A structure of a border area in a write-once type information storagemedium will be described here with reference to FIG. 40. When one borderarea has been first set in the write-once information storage medium, anbordered area (Bordered Area) BRDA#1 is set at the inner periphery size(which is the closest to the data lead-in area DTLDI), as shown in FIG.40 (a), and then, a border out (Border out) BRDO that follows the abovearea is formed.

Further, in the case where an attempt is made to set a next borderedarea (Bordered Area) BRDA#2, as shown in FIG. 40 (b), a next (#1) borderin area BRDI that follows the preceding #1 border out area BRDO isformed, and then, a next bordered area BRDA#2 is set. In the case wherean attempt is made to close the next bordered area BRDA#2, a (#2) borderout area BRDO that immediately follows the area BRDA#2 is formed. In thepresent embodiment, a state in which the next ((#1) border in area BRDI)that follows the preceding (#1) border out area BRDO is formed andcombined is referred to as a border zone BRDZ. The border zone BRDZ isset to prevent an optical head from overrun between the bordered areasBRDAs when reproduction has been carried out by using the informationreproducing apparatus (on the presumption that the DPD detectingtechnique is used). Therefore, in the case where a write-once typeinformation storage medium having information recorded therein isreproduced by using a read-only apparatus, it is presumed that a borderclose process is made such that the border out area BRDO and border-inarea BRDI are already recorded and the border out area BRDO that followsthe last bordered area BRDA is recorded. The first bordered area BRDA#1is composed of 4080 or more physical segment blocks, and there is a needfor the first bordered area BRDA#1 to have a width of 1.0 mm or more ina radial direction on the write-once type information storage medium.FIG. 40 (b) shows an example of setting an expanded drive test zoneEDRTZ in the data area DTA.

FIG. 40 (c) shows a state obtained after finalizing a write-onceinformation storage medium. FIG. 40 (c) shows an example in which anexpanded drive test zone EDRTZ is incorporated in the data lead-out areaDTLDO, and further, an expanded spare area ESPA has been set. In thiscase, a user data adding enable range 205 is fully padded with the lastborder out area BRDO.

FIG. 40 (d) shows a detailed data structure in the border zone area BRDZdescribed above. Each item of information is recorded in size units ofone physical segment blocks (physical segment block). Copy informationC_RMZ on the contents recorded in a recording management zone isrecorded at the beginning of the border out area BRDO, and a border endmark (Stop Block) STB indicating the border out area BRDOP is recorded.Further, in the case the next border in area BDI is reached, a firstmark (Next Border Marker) NBM indicating that a next border area reachesan “N1-th” physical segment block counted from a physical segment blockin which the border end mark (Stop Block) STC has been recorded; asecond mark NBM indicating that a next border region reaches an “N2-th”physical segment block; and a third mark NBM indicating that a nextborder region reaches an “N3-th” mark NBM are discretely recorded in atotal of three locations on a size by size basis of one physical segmentblock, respectively. Updated physical format information U_PFI isrecorded in the next border-in area BRDI. In a current DVD-R or a DVD-RWdisk, in the case where a next border is not reached (in the last borderout area BRDO), a location in which “a mark NBM indicating a nextborder” should be recorded (a location of one physical segment blocksize) shown in FIG. 40 (d) is maintained as a “location in which no datais recorded”. If border closing is carried out in this state, thiswrite-once type information storage medium (current DVD-R or DVD-RWdisk) enters a state in which reproduction can be carried out by using aconventional DVD-ROM drive or a conventional DVD player. Theconventional DVD-ROM drive or the conventional DVD player utilizes arecording mark recorded on this write-once type information storagemedium (current DVD-R or DVD-RW disk) to carry out track shift detectionusing the DPD (Differential Phase Detect) technique. However, in theabove described “location in which no data is recorded”, a recordingmark does not exist over one physical segment block size, thus making itimpossible to carry out track shift detection using the DPD(Differential Phase Detect) technique. Thus, there is a problem that atrack servo cannot be stably applied. In order to solve the abovedescribed problem with the current DVD-R or DVD-RW disk, the presentembodiment newly employed methods for:

1) in the case where a next border area is reached, recording data on aspecific pattern in advance in a “location in which the mark NBMindicating a next border should be recorded”; and

2) carrying out an “overwriting process” in a specific recording patternpartially and discretely with respect to a location indicating “the markNBM indicating a next border” in which, in the case where a next borderarea is reached, the data on the specific pattern is recorded inadvance, thereby utilizing identification information indicating that “anext border area is reached”.

By setting a mark indicating a next border due to overwriting, there isattained advantageous effect that, even in the case where a next borderarea is reached as shown in item (1), a recording mark of a specificpattern can be formed in advance in a “location in which the mark NBMindicating a next border should be recorded”, and, after border closing,even if a read-only type information reproducing apparatus carries outtrack shift detection in accordance with the DPD technique, a trackservo can be stably applied. If a new recording mark is overwrittenpartially on a portion at which a recording mark has already been formedin a write-once type information storage medium, there is a danger thatthe stability of a PLL circuit shown in FIG. 11 is degraded in aninformation recording/reproducing apparatus or an informationreproducing apparatus. In order to overcome this danger, the presentembodiment further newly employs methods for:

3) when overwriting is carried out at a position of “the mark NBMindicating a next border” of one physical segment block size, changingan overwrite state depending on a location contained in the same datasegment;

4) partially carrying out overwriting in a sync data 432 and disablingoverwriting on a sync code 431; and

5) carrying out overwriting in a location excluding data ID and IED.

As described later in detail, data fields 411 to 418 for recording userdata and guard areas 441 to 448 are alternately recorded on aninformation storage medium. A group obtained by combining the datafields 411 to 418 and the guard areas 441 to 448 is called a datasegment 490, and one data segment length coincides with one physicalsegment block length. The PLL circuit 174 shown in FIG. 11 facilitatesPLL lead-in in VFO areas 471 and 472 in particular. Therefore, even ifPLL goes out immediately before the VFO areas 471 and 472, PLLre-lead-in is easily carried out by using the VFO areas 471 and 472,thus reducing an effect on a whole system in the informationrecording/reproducing apparatus or information reproducing apparatus.There is attained advantageous effect that (3) an overwrite state ischanged depending on a location in a data segment internal location, asdescribed above, by utilizing this state, and an overwrite amount of aspecific pattern is increased at a back portion close to the VFO areas471 and 472 contained in the same data segment, thereby making itpossible to facilitate judgment of “a mark indicating a next border” andto prevent degradation of the precision of a signal PLL at the time ofreproduction. As described in detail with respect to FIGS. 83 (a) to 83(f) and FIGS. 62 (a) and 62 (b), one physical sector is composed of acombination of a location in which sync codes (SY0 to SY3) are arrangedand the sync data 434 arranged between these sync codes 433. Theinformation recording/reproducing apparatus or the information recordingapparatus samples sync codes 43 (SY0 to SY3) from a channel bit patternrecorded on the information storage medium, and detects a boundary ofthe channel bit pattern. As described later, position information(physical sector numbers or logical sector numbers) on the data recordedon the information storage medium is sampled from data ID information. Adata ID error is sensed by using an IED arranged immediately after thesampled information. Therefore, the present embodiment enables (5)disabling overwriting on data ID and IED and (4) partially carrying outoverwriting in the sync data 432 excluding the sync code 431, therebyenabling detection of a data ID position and reproduction(content-reading) of the information recorded in data ID by using thesync code 431 in the “mark NMB indicating a next border”.

FIG. 39 shows another embodiment which is different from that shown inFIG. 40 relating to a structure of a border area in a write-once typeinformation storage medium. FIGS. 39 (a) and 39 (b) show the samecontents of FIGS. 40 (a) and 40 (b). FIG. 39 (a) to 39 (d) are differentfrom FIG. 40 (c) in terms of a state that follows finalization of awrite-once type information storage medium. For example, as shown inFIG. 39 (c), after information contained in the bordered area BRDA#3 hasbeen recorded, in the case where an attempt is made to achievefinalization, a border out area BRDO is formed immediately after thebordered area BDA#3 as a border closing process. Then, a terminator areaTRM is formed after the border out area DRDO which immediately followsthe bordered area BRDA#3, thereby reducing a time required forfinalization. In the embodiment shown in FIG. 40, there is a need forpadding a region that immediately precedes the expanded spare area ESPAwith border out area BRDO. There occurs a problem that a large amount oftime is required to form this border out area BRDO, thereby expandingthe finalization time. In contrast, in the embodiment shown in FIG. 39(c), a comparatively short terminator area TRM is set in length; all ofthe outer areas than the terminator TRM are redefined as a data lead-outarea NDTLDO; and an unrecorded portion which is outer than theterminator TRM is set as a user disable area 911. That is, when the dataarea DTA is finalized, the terminator area TRM is formed at the end ofrecording data (immediately after the border out area BRDO). All theinformation on the main data contained in this area is set to “00h”.Type information on this area is set in an attribute of the datalead-out area NDTLDO, whereby this terminator area TRM is redefined as anew data lead-out area NDTLDO, as shown in FIG. 39 (c). Type informationon this area is recorded in area type information 935 contained in dataID, as described later. That is, the area type information 935 containedin the data ID in this terminator area TRM is set to “1b”, as shown inFIGS. 50 (a) to 50 (d), thereby indicating that data exists in the datalead-out area DTLDO. The present embodiment is featured in thatidentification information on a data lead-out position is set by thedata ID internal area type information 935. In an informationrecording/reproducing apparatus or an information reproducing apparatusshown in FIG. 11, let us consider a case in which an informationrecording/reproducing unit 141 has provided a random access to aspecific target position on a write-once type information storagemedium. Immediately after random access, the informationrecording/reproducing unit 141 must reproduce a data ID and decode adata frame number 922 in order to know where on the write-once typeinformation storage medium has been reached. In the data ID, area typeinformation 935 exists near the data frame number 922. At the same time,it is possible to immediately identify whether or not the informationrecording/recording unit 141 exists in the data lead-out area DTLDOmerely by decoding this area type information 935. Thus, asimplification and high speed access control can be made. As describedabove, identification information on the data lead-out area DTLDO isprovided by data ID internal setting of the terminator area TRM, therebymaking it easy to detect the terminator area TRM.

As a specific example, in the case where the border out area BRDO is setas an attribute of the data lead-out area NDTLDO (that is, in the casewhere the area type information 935 contained in the data ID of a dataframe in the border out BRDO is set to “10 b”), the setting of thisterminator area TRM is not provided. Therefore, when the terminator areaTRM is recorded, the area having an attribute of the data lead-out areaNDTLDO, this terminator area TRM is regarded as part of the datalead-out area NDTLDO, thus disabling recording into the data area DTA.As a result, as in FIG. 39 (c), a user disable area 911 may remain.

In the present embodiment, the size of the terminator area TRM ischanged depending on a location on a write-once type information storagemedium, thereby reducing a finalization time and achieving efficientprocessing. This terminator area TRM indicates an end position ofrecording data. In addition, even in the case where this area is used ina read-only apparatus, which carries out track shift detection inaccordance with a DPD technique, the terminator area, is utilized toprevent overrun due to a track shift. Therefore, a width in a radialdirection on the write-once type information storage medium having thisterminator area TRM (width of a portion padded with the terminator areaTRM) must be a minimum of 0.05 nm or more because of the detectioncharacteristics of the read-only apparatus. A length of one cycle on thewrite-once type information storage medium is different depending on aradial position, and thus, the number of physical segment blocksincluded in one cycle is also different depending on the radialposition. Thus, the size of the terminator area TRM is differentdepending on the physical sector number of a physical sector which ispositioned at the beginning of the terminator area TRM, and the size ofthe terminator area TRM increases as the physical sector go to the outerperiphery side. A minimum value of a physical sector number of anallowable terminator area TRM must be greater than “04FE00h”. Thisderived from a restrictive condition in which the first bordered areaDRDA#1 is composed of 4080 or more physical segment blocks, making itnecessary for the first bordered area BRDA#1 to have a width equal to orgreater than 1.0 mm in a radial direction on the write-once typeinformation storage medium. The terminator area TRM must start from aboundary position of physical segment blocks.

In FIG. 39 (d), a location in which each item of information is to berecorded is set for each physical segment block size for the reasondescribed previously, and a total of 64 KB user data recorded to bedistributed in 32 physical sectors is recorded in each physical segmentblock. A relative physical segment block number is set with respect to arespective one item of information, as shown in FIG. 39 (d), and theitems of information are sequentially recorded in the write-once typeinformation storage medium in ascending order from the lowest relativephysical segment number. In the embodiment shown in FIGS. 39 (a) to 39(d), copies CRMD#0 to CRMD#4 of RMD, which are the same contents, areoverwritten five times in a copy information recording zone C_TRZ of thecontents recorded in the recording management zone shown in FIG. 40 (d).The reliability at the time of reproduction is improved by carrying outsuch overwriting, and, even if dust or scratch adheres onto a write-onceinformation storage medium, the copy information CRMD on the contentsrecorded in the recording management zone can be stably reproduced.Although the border end mark STB shown in FIG. 39 (d) coincides with aborder end mark STB shown in FIG. 40 (d), the embodiment shown in FIG.39 (d) does not have the mark NBM indicating a next border, unlike theembodiment shown in FIG. 40 (d). All the information on the main datacontained in reserved areas 901 and 902 is set to “00h”.

At the beginning of the border-in area BRDI, information which iscompletely identical to updated physical format information U_PFI ismultiply written six times from N+1 to N+6, configuring the updatedphysical format information U_PFI shown in FIG. 40. The thus updatedphysical format information U_PFI is multiply written, thereby improvingthe reliability of information.

In FIG. 39 (d), the present embodiment is featured in that the recordingmanagement zone RMZ in the border zone is provided in the border-in areaBRDI. As shown in FIG. 36 (a), the size of the recording management zoneRMZ contained in the data lead-in area DTLDI is comparatively small. Ifthe setting of a new bordered area BRDA is frequently repeated, therecording management data RMD recorded in the recording management zoneRMZ is saturated, making it impossible to set a new bordered area BRDAmidway. As in the embodiment shown in FIG. 39 (d), there is attainedadvantageous effect that a recording management zone for recording therecording management data RMD relating to the bordered area BRDA#3 thatfollows is provided in the border-in area DRDI, whereby the setting of anew bordered area BRDA can be provided a number of times and theadditional writing count in the bordered area BRDA can be significantlyincreased. In the case where the bordered area BRDA#3 that follows theborder-in area BRDI including the recording management zone RMZ in thisborder zone is closed or in the case where the data area DTA isfinalized, it is necessary to repeatedly record all the last recordingmanagement data RMD into a spare area 273 (FIG. 38 (b)) established inan unrecorded state in the recording management zone RMZ, and pad allthe spare area with the data. In thins manner, the spare area 273 in an(unrecorded state can be eliminated, a track shift (due to DPD) at thetime of reproduction in a read-only apparatus can be prevented, and thereproduction reliability of the recording management data RMD can beimproved by multiple recording of the recording management data. All thedata contained in a reserve area 903 are set to “00h”.

Although the border out area BRDO serves to prevent overrun due to atrack shift in the read-only apparatus while the use of DPD is presumed,there is no need for the border-in area BRDI to have a particularlylarge size other than having the updated physical format informationU_PFI and the information contained in recording management zone RMZ inthe border zone. Therefore, an attempt is made to reduce the size to theminimum in order to reduce a time (required for border zone BRDZrecording) at the time of setting a new bordered area BRDA. With respectto FIG. 39 (a), before forming the border out area BRDO due to borderclosing, there is a high possibility that the user data additionalwriting enable range 205 is sufficiently large, and a large number ofadditional writing is carried out. Thus, it is necessary to largely takea value of “M” shown in FIG. 39 (d) so that recording management datacan be recorded a number of times in the recording management zone RMZin a border zone. In contrast, with respect to FIG. 39 (b), in a statethat precedes border closing of the bordered area BRDA#2 and thatprecedes recording the border out area BRDO, the user data additionalwriting enable range 205 narrows, and thus, it is considered that notthe number of additional writings of the recording management data to beadditionally written in the recording management zone RMZ in the borderzone does not increase so much. Therefore, the setting size “M” of therecording management zone RMZ in the border-in area BRDI thatimmediately precedes the bordered area BRDA#2 can be taken to berelatively small. That is, as a location in which the border-in areaBRDI is arranged goes to the inner periphery side, the number ofpredicted additional writings of the recording management dataincreases. As the location goes to the outer periphery, the number ofpredicted additional writings of the recording management datadecreases. Thus, the present embodiment is featured in that the size ofthe border-in area BRDI is reduced. As a result, the reduction of a timefor setting a new bordered area BRDA and processing efficiency can beachieved.

A logical recording unit of the information recorded in the borderedarea BRDA shown in FIG. 40 (c) is referred to as an R zone. Therefore,one bordered area BRDA is composed of at least one or more R zones. In acurrent DVD-ROM, as a file system, there are employed a file systemcalled a “UDF bridge” in which both of file management information whichconforms with a UDF (Universal Disc Format) and file managementinformation which conforms with ISO 9660 are recorded in one informationstorage medium at the same time. In a file management method whichconforms with ISO 9660, there is a rule that one file must becontinuously recorded in an information storage medium. That is,information contained in one file is disabled to be divisionallyarranged at a discrete position on an information storage medium.Therefore, for example, in the case where information has been recordedin conformance with the above UDF bridge, all the informationconfiguring one file is continuously recorded. Thus, it is possible toadapt this area in which one file is continuously recorded so as toconfigure one R zone.

FIG. 41 shows a data structure in the control data zone CDZ and theR-physical information zone RIZ. As shown in FIG. 41 (b), physicalformat information (PFI) and disc manufacturing information (DMI) existin the control data zone CDZ, and similarly, an DMI (Disc ManufacturingInformation) and R_PFI (R-Physical Format Information) are contained inan R-physical information zone RIZ.

Information 251 relating to a medium manufacture country and mediummanufacturer's nationality information 252 are recorded in mediummanufacture related information DMI. When a commercially availableinformation storage medium infringes a patent, there is a case in whichan infringement warning is supplied to such a country in which amanufacturing location exists or an information storage medium isconsumed (or used). A manufacturing location (country name) isidentified by being obliged to record the information contained in aninformation storage medium, and a patent infringement warning is easilysupplied, whereby an intellectual property is guaranteed, and technicaladvancement is accelerated. Further, other medium manufacture relatedinformation 253 is also recorded in the medium manufacture relatedinformation DMI.

The present embodiment is featured in that type of information to berecorded is specified depending on a recording location (relative byteposition from the beginning) in physical format information PFI orR-physical format information R_PFI. That is, as a recording location inthe physical format information PFI or R-physical format informationR_PFI, common information 261 in a DVD family is recorded in an 32-bytearea from byte 0 to byte 31; common information 262 in an HD_DVD familywhich is the subject of the present embodiment is recorded in 96 bytesfrom byte 32 to byte 127; unique information (specific information) 263relating to various specification types or part versions are recordingin 384 bytes from byte 128 to byte 511; and information corresponding toeach revision is recorded in 1536 bytes from byte 512 to byte 2047. Inthis way, the information allocation positions in the physical formatinformation are used in common depending on the contents of information,whereby the locations of the recorded information are used in commondepending on medium type, thus making it possible to carry out in commonand simplify a reproducing process of an information reproducingapparatus or an information recording/reproducing apparatus. The commoninformation 261 in a DVD family recorded in byte 0 to byte 31, as shownin FIG. 41D, is divided into: information 267 recorded in common in allof a read-only type information storage medium and a rewritable-typeinformation storage medium, and a write-once type information storagemedium recorded from byte 0 to byte 16; and information 268 which isrecorded in common in the rewritable-type information storage medium andthe write-once type information storage medium from byte 17 to byte 31and which is not recorded in the read-only type medium.

FIG. 55 shows another embodiment relating to a data structure in thecontrol data zone shown in FIG. 41. As shown in FIG. 35C, the controldata zone CDZ is configured as part of an emboss bit area 211. Thiscontrol data zone CDZ is composed of 192 data segments start fromphysical sector number 151296 (024F00h). In the embodiment shown in FIG.55, a control data section CTDS composed of 16 data segments and acopyright data section CPDS composed of 16 data segments are arranged ontwo by two basis in the control data zone CDZ, and a reserve area RSV isset between these two sections. By allocating these sections on a two bytwo basis, a physical distance between the two sections is widened, andan effect relevant to a burst error which occurs due to a scratch of aninformation storage medium surface or the like is reduced.

In one control data section CTDS, as shown in FIG. 55 (c), physicalsector information on first three relative sector numbers “0” to “2” isrecorded to be repeated 16 times. Multiple writing is carried out 16times, thereby improving the reliability of recording information.Physical format information PFI described in FIG. 42 or 54 is recordedin a first physical sector in a data segment whose relative physicalsector number is “0”. Disk manufacture related information DMI isrecorded in a second physical sector in a data segment whose relativephysical sector number is “1”. Furthermore, copyright protectioninformation CPI is recorded in the third physical sector in the datasegment in which relative number of the physical sector is “2”. Areserved area RSV whose relative physical sector number is “3” to “31”is reserved so as to be available in a system.

As the contents of the above described disk manufacture relatedinformation DMI, a disk manufacturer's name (Disc Manufacturer's name)is recorded in 128 bytes from byte 0 to byte 127; and information on alocation in which a manufacturer exists (information indicating wherethis disk has been manufactured” is recorded in 128 bytes from byte 128to byte 255.

The above disk manufacturer's name is described in ASCII codes. However,the ASCII codes available in use as a disk manufacturer's name arelimited to a starting byte to “0Dh” and “20h” to “7Eh”. A diskmanufacture's name is described from the first byte 1 in this area, andthe remaining portions in this area are padded (terminated) with data“0Dh”.

With respect to information on a location in which the above diskmanufacturer exists, the information indicating where this disk has beenmanufactured, a country or a region is described in the ASCII codes.This area is limited to a starting byte to “0Dh” and “20h” to “7Eh”which are available ASCII codes as in the disk manufacturer's name. Theinformation on a location in which a disk manufacturer exists isdescribed from the first byte 1 in this area, and the remaining portionsin this area are padded (terminated) with data “0Dh”. Alternatively,another describing method includes setting an allowable size in therange of the first byte to “0Dh” as the information on a location inwhich a disk manufacturer exists. In the case where the information on alocation in which a disk manufacturer exists is long, the information isterminated at “0Dh”, and a region subsequent to “0Dh” may be padded withdata “20h”.

The reserved area RSV shown in FIG. 55 (c) is fully padded with data“00h”.

FIG. 42 shows a comparison depending on a medium type (read-only type,rewritable-type, or write-once type) of information contained in thephysical format information PFI with the contents of specificinformation contained in the physical format information PFI orR-physical format information R_PFI shown in FIG. 41 or FIG. 55. Asinformation 267 recorded in common to all of the read-only type,rewritable-type, and write-once type medium in the common information261 in the DVD family, there are sequentially recorded from bytepositions 0 to 16: specification type (read-only, rewriting, orwrite-once) information and version number information; medium size(diameter) and maximum allowable data transfer rate information; amedium structure (single layer or double layer or whether or not embosspit, additional writing area, or rewriting area exists); a recordingdensity (line density and track density) information; allocationlocation information on data region DTA; and information on whether ornot burst cutting area BCA exists (both of them exist in the presentembodiment).

As information 268 in common information 261 of a DVD family andrecorded in common to a rewriting type and a write-once type, there arerecorded: revision number information for sequentially defining amaximum recording speed from byte 28 to byte 31; revision numberinformation for defining a maximum recording speed; a revision numbertable (application revision number); class state information andexpanded (part) version information. The embodiment is featured in thatthe information contained from byte 28 to byte 31 include revisioninformation according to a recording speed in a recording area ofphysical format information PFI or R-physical format information R_PFI.Conventionally, upon development of a medium featured in that a mediumrecording speed such as ×2 or ×4 increases, there has been a verycomplicated inconvenience that a specification is newly draftedconcurrently. In contrast, according to the present embodiment, thereare divisionally provided: a specification (version book) in which aversion is changed when the contents have been significantly changed;and a revision book in which the corresponding revision is changed andissued, and only a revision book is issued, the book having updated onlyrevision every time a recording speed is improved. In this manner, anexpanding function for a medium which supports high speed recording anda specification can be handled by a simple method called revisionchange. Thus, in the case where a high speed recording compatible mediumhas been newly developed, there is attained advantageous effect thathigh speed recording can be carried out. In particular, the presentembodiment is featured in that revision numbers can be separately set bya maximum value and a minimum value by separately providing a field ofrevision number information defining a maximum recording speed of byte17 and a field of revision number information defining a minimumrecording speed of byte 18. For example, in the case where a recordingfilm capable of carrying out recording at a very high speed has beendeveloped, that recording film is often very expensive. In contrast, asin the present embodiment, revision numbers are separately set dependingon a maximum value and a minimum value of a recording speed, therebyincreasing options of recording mediums which can be developed. As aresult, there is attained advantageous effect that a medium capable ofcarrying out high speed recording or a more inexpensive medium can besupplied. An information recording/reproducing apparatus according tothe present embodiment has in advance information on an allowablemaximum recording speed and an allowable minimum recording speed foreach revision. When an information storage medium is mounted on thisinformation recording/reproducing apparatus, first, the informationrecording/reproducing unit 141 shown in FIG. 11 reads the informationcontained in this physical format information PFI and R-physical formatinformation R_PFI. Based on the obtained revision number information,there are detected by the control unit 143: an allowable maximum speedand an allowable minimum recording speed of an information storagemedium mounted with reference to information on an allowable maximumrecording speed and an allowable minimum recording speed for eachrevision recorded in advance in the memory unit 175; and recording iscarried out at an optimal recording speed based on the result of theidentification.

Now, a description will be given with respect to the significance ofspecific information 263 of the type and version of each of thespecifications from byte 128 to byte 511 shown in FIG. 41 (c) and thesignificance of information content 264 which can be set specific toeach of the revisions from byte 512 to byte 2047. That is, in thespecific information 263 of type and version of each of thespecifications from byte 128 to byte 511, the significance of thecontents of recording information at each byte position coincides with arewritable-type information storage medium of a different typeregardless of a write-once type information storage medium. Theinformation content 264 which can be set specific to each of therevisions from byte 512 to byte 2047 permits the fact that if a revisionis different from another in the same type of medium as well as adifference between a rewritable-type information storage medium and awrite-once type information storage medium whose types are differentfrom each other, the significances of the contents of recordinginformation at byte positions are different from each other.

As shown in FIG. 42, as information contents in the specific information263 on the type and version of each of the specifications which coincidewith each other in significance of the contents of recording informationat byte positions between the rewritable-type information storage mediumand the write-once type information storage medium whose types aredifferent from each other, there are sequentially recorded: diskmanufacturer's name information; additional information from the diskmanufacturer; recording mark polarity information (identification of“H-L” or “L-H”); line speed information at the time of recording orreproduction; a rim intensity value of an optical system along a radialdirection; and recommended laser power at the time of reproduction(light amount value on recording surface).

In particular, the present embodiment is featured in that recording markpolarity information (Mark Polarity Descriptor (identification of “H-L”or “L-H”) is provided in byte 192. In the conventional rewritable-typeor write-once DVD disk, only a “H-L” (High to Low) recording film whoselight reflection amount in a recording mark is low with respect to anunrecorded state (a state in which reflection level is relatively high:High) has been accepted. In contrast, if a medium requires “high speedrecording compatibility”, “price reduction” or “decrease in cross-erase”and “increase in upper limit value of rewriting count” which arephysical properties, there is a problem that the conventional “H-L”recording film is insufficient. In contrast, the present embodimentallows use of an “L-H” recording film whose light reflection amountincreases in a recording mark as well as only an “H-L” recording film.Thus, there is attained advantageous effect that the “L-H” recordingfilm as well as the conventional “H-L” film is incorporated in thespecification, and selecting options of the recording films areincreased, thereby making it possible to achieve high speed recording orto supply an inexpensive medium.

A specific method for mounting an information recording/reproducingapparatus will be described below. The specification (version book) orrevision book describe both of the reproduction signal characteristicsderived from the “H-L” recording film and the reproduction signalcharacteristics derived from the “L-H” recording film. Concurrently, thecorresponding circuits are provided on a two by two basis in the PRequalizing circuit 130 and Viterbi decoder 156 shown in FIG. 11. When aninformation storage medium is mounted in the information reproductionunit 141, first, the slice level detector circuit 132 for reading theinformation contained in the system lea-in area SYLDI is started up.This slice level detector circuit 132 reads information on polarity of arecording mark recorded in this 192 byte (identification of “H-L” or“L-H”); and then make judgment of “H-L” or “L-H”. In response to thejudgment, after the PR equalizing circuit 130 and a circuitry containedin the Viterbi decoder 156 has been switched, the information recordedin the data lead-in area DTLDI or data area DTA is reproduced. The abovedescribed method can read the information contained in the data lead-inarea DTLDI or data area DTA comparatively quickly, and moreover,precisely. Although revision number information defining a maximumrecording speed is described in byte 17 and revision number informationdefining a minimum recording speed is described in byte 18, these itemsof information are merely provided as range information defining amaximum and a minimum. In the case where the most stable recording iscarried out, there is a need for optimal line speed information at thetime of recording, and thus, the associated information is recorded inbyte 193.

The present embodiment is featured in that information on a rimintensity value of an optical system along a circumferential directionof byte 194 and information on a rim intensity value of an opticalsystem along in a radial direction of byte 195 is recorded as opticalsystem condition information at a position which precedes information ona variety of recording conditions (write strategies) included in theinformation content 264 set specific to each revision. These items ofinformation denote conditional information on an optical system of anoptical head used when identifying a recording condition arranged at theback side. The rim intensity used here denotes a distribution state ofincident light incident to an objective lens before focusing on arecording surface of an information storage medium. This intensity isdefined by a strength value at a peripheral position of an objectivelens (iris face outer periphery position) when a center intensity of anincident light intensity distribution is defined as “1”. The incidentlight intensity distribution relevant to an objective lens is notsymmetrical on a point to point basis; an elliptical distribution isformed; and the rim intensity values are different from each otherdepending on the radial direction and the circumferential direction ofthe information storage medium. Thus, two values are recorded. As therim intensity value increases, a focal spot size on a recording surfaceof the information storage medium is reduced, and thus, an optimalrecording power condition changes depending on this rim intensity value.The information recording/reproducing apparatus recognizes in advancethe rim intensity value information contained in its own optical head.Thus, this apparatus reads the rim intensity values of the opticalsystem along the circumferential direction and the radial direction, thevalue being recorded in the information storage medium, and comparesvalues of its own optical head. If there is no large difference as aresult of the comparison, a recording condition recorded at the backside can be applied. If there is a large difference, there is a need forignoring the recording condition recorded at the back side and startingidentifying an optimal recording condition while therecording/reproducing apparatus carries out test writing by utilizingthe drive test zone DRTZ shown in FIGS. 35B, 35C, 37A to 37F.

Therefore, there is a need for quickly making a decision as to whetherto utilize the recording condition recorded at the back side or whetherto start identifying the optimal recording condition while ignoring theinformation and carrying out test writing by oneself. As shown in FIG.42, there is attained advantageous effect that the rim intensityinformation can be read, and then judgment can be made at a high speedas to whether or not the recoding condition arranged later is met byarranging conditional information on an optical system identified at apreceding position with respect to a position at which the recommendedrecording condition has been recorded.

As described above, according to the present embodiment, there aredivisionally provided: a specification (version book) in which a versionis changed when the contents have been significantly changed; and arevision book in which the corresponding revision is changed and issued,and only a revision book is issued, the book having updated onlyrevision every time a recording speed is improved. Therefore, if arevision number is different from another, a recording condition in arevision book changes. Thus, information relating to a recordingcondition (write strategy) is mainly recorded in the information content264 which can be set specific to each of the revisions from byte 512 tobyte 2047. As is evident from FIG. 42, the information content 264 whichcan be set specific to each of the revisions from byte 512 to byte 2047permits the fact that if a revision is different from another in thesame type of medium as well as a difference between a rewritable-typeinformation storage medium and a write-once type information storagemedium whose types are different from each other, the significances ofthe contents of recording information at byte positions are differentfrom each other.

Definitions of peak power, bias power 1, bias power 2, and bias power 3shown in FIG. 42 coincide with power values defined in FIG. 18. An endtime of a first pulse shown in FIG. 42 denotes T_(EFP) defined in FIG.18; a multi-pulse interval denotes T_(MP) defined in FIG. 18; a starttime of a last pulse denotes T_(SLP) defined in FIG. 38, and a period ofbias power 2 of 2 T mark denotes T_(LC) defined in FIG. 18.

FIG. 54 shows another embodiment relating to a data structure in each ofphysical format information and R-physical format information. Further,FIG. 54 comparatively describes “updated physical format information”.In FIG. 54, byte 0 to byte 31 are utilized as a recording area of commoninformation 269 contained in a DVD family, and byte 32 and subsequentare set for each specification.

In a write-once type information storage medium, as shown in FIG. 35C,with respect to R-physical format information recorded in an R-physicalinformation zone RIZ contained in the data lead-in area DTLDI, borderzone start position information (first border outermost peripheryaddress) is added to the physical format information PFI (copy of HD_DVDfamily common information), and the added information is described. Inthe updated physical format information U_PFI, updated in the border-inarea BRDI shown in FIG. 40 or 39, start position information(self-border outermost periphery address) is added to the physicalformat information (copy of HD_DVD family common information), and theadded information is recorded. In FIG. 42, this border zone startposition information is recorded from byte 197 to byte 204. In contrast,the embodiment shown in FIG. 54 is featured in that information isrecorded at byte 133 to byte 140 which are positions precedinginformation relating to a recording condition such as peak power or biaspower 1 (information content 264 which can be set specific to eachrevision), the position following the common information 269 containedin the DVD family. The updated start position information is alsoarranged in byte 133 to byte 140 which are positions precedinginformation relating to a recording condition such as peak power or biaspower 1 (information content 264 which can be set specific to eachrevision), the position following the common information 269 containedin the DVD family. If revision number is upgraded and a recordingcondition for high precision is required, there is a possibility thatthe recording condition information contained in the rewritable-typeinformation storage medium uses byte 197 to byte 207. In this case, asin the embodiment shown in FIG. 42, if the border zone start positioninformation for R-physical format information recorded in the write-oncetype information storage medium is arranged in byte 197 to byte 204,there is a danger that a correlation (compatibility) between therewritable-type information storage medium and the write-once typeinformation storage medium relating to the arranged position of therecording condition is distorted. As shown in FIG. 54, there is attainedadvantageous effect that the border zone start position information andthe updated start position information are arranged in byte 133 to byte140, thereby making it possible to record a correlation (compatibility)in recording position of a variety of information between therewritable-type information storage medium and the write-once typeinformation storage medium even if an amount of information relating toa recording condition will be increased in the future. With respect tothe specific contents of information relating to the borer zone startposition information, the start position information on the border outarea BRDO situated at the outside of the (current) bordered area BRDAcurrently used in byte 133 to byte 136 is described in PSN (PhysicalSector Number); and border-in area BRDI start position informationrelating to the bordered area BRDA to be used next is described in thephysical sector number (PSN) in byte 137 to byte 140.

The specific contents of information relating to the updated startposition information indicate the latest border zone positioninformation in the case where a bordered area BRDA has been newly set.The start position information on the border out area BRDO situated atthe outside of the (current) bordered area BRDA currently used in byte133 to byte 136 is described in PSN (Physical Sector Number); and thestart position information on the border-in area BRDI relating to thebordered area BRDA to be used next is described in the sector number(PSN) in byte 137 to byte 140. In the case where recording cannot becarried out in the next bordered area BRDA, this area (ranging from byte137 to byte 140) is padded with all “00h”.

As compared with the embodiment shown in FIG. 42, in the embodimentshown in FIG. 54, “medium manufacturer's name information” and“additional information from medium manufacturer” are erased, andrecording mark polarity information (identification of “H-L” or “L-H”)is arranged in 128 byte and subsequent.

FIG. 43 shows a comparison of the contents of detailed informationrecorded in the allocation location information on the data area DTArecorded in byte 4 to byte 15 shown in FIG. 42 or 54. The start positioninformation on the data area DTA is recorded in common regardless ofidentification of medium type, physical format information PFI, andR-physical format information R_PFI. As information indicating an endposition, end position information on the data area DTA is recorded in aread-only type information storage medium.

End position information on an additional writing enable range of theuser data is recorded in the physical format information PFI containedin the write-once type storage medium. This positional informationdenotes a position that immediately precedes point δ in an example shownin FIG. 37E, for example.

In contrast, the R-physical format information R_PFI contained in thewrite-once type information storage medium records the end positioninformation on the recorded data contained in the corresponding borderedarea BRDA.

Further, the read-only type information storage medium records the endaddress information contained in “layer 0” which is a front layer whenseen from the reproduction optical system; and the rewritable-typeinformation storage medium records information on a differential valueof each item of start position information between a land area and agroove area.

As shown in FIG. 35C, a recording management zone RMZ exists in the datalead-in area DTLDI. In addition, as shown in FIG. 40 (d), the associatedcopy information exists in the border-out zone BRDO as copy informationC_RMZ indicating the contents recorded in the recording management zone.This recording management zone RMZ records RMD (Recording ManagementData) having the same data size as one physical segment block size, asshown in FIG. 36 (b), so that new recording management data RMD updatedevery time the contents of the recording management data RMD is updatedcan be sequentially added backwardly. A detailed data structure in suchone item of recording management data RMD is shown in each of FIGS. 44,45, 46, 47, 48 and 49. The recording management data RMD is furtherdivided into fine RMD field information RMDF of 2048 byte size.

The first 2048 bytes in the recording management data are provided as areserved area. The next RMD field 0 of 2048 byte size sequentiallyallocates: format code information of recording management data RMD;medium state information indicating a state of the target medium, i.e.,(1) in an unrecorded state, (2) on the way of recording beforefinalizing, or (3) after finalizing; unique disk ID (disk identificationinformation); allocation position information on the data region DTA;allocation position information on the latest (updated) data area DTA;and allocation position information on recording management data RMD.The allocation position information on the data area records informationindicating a user data additional writing enable range 204 (FIG. 37D),i.e., start position information on the data area DTA and the endposition information on the user data recording enable range 204 at thetime of an initial state. In the embodiment shown in FIG. 37D, thisinformation indicates a position that immediately precedes point β.

The present embodiment, as shown in FIGS. 37E and 37F, is featured inthat an expanded drive test zone EDRTZ and an expanded spare area ESPAcan be additionally set in the user data additional writing enable range204. However, such expansion narrows a user data additional writingenable range 205. The present embodiment is featured in that associatedinformation is recorded in “allocation position information on thelatest (updated) data area DTA” so as not to additionally write the userdata in these expanded areas EDRTZ and ESPA. That is, it is possible toidentify whether or not the expanded drive test zone EDRTZ has beenexpanded based on the identification information on the presence orabsence of the expanded drive test zone EDRTZ, and it is possible toidentify whether or not the expanded spare area ESPA has been expandedbased on identification information on the presence or absence of theexpanded spare area ESPA. Further, the recording enable rangeinformation relating to the user data additional writing enable range205 managed in the recording management data RMD includes an endposition of the latest user data recording enable range 205 recorded inthe allocation position information on the data area DTA. Therefore, theuser data recording enable range 205 shown in FIG. 37F can be identifiedimmediately, enabling high speed detection of a size of an unrecordedarea in which recording can be carried out in the future (the residualamount of unrecorded area). In this manner, for example, there isattained advantageous effect that a transfer rate at the time of optimalrecording is set in conformance with the user specified image recordingreserved time, thereby making it possible to fully record an image in amedium during the user specified image recording reserved time. By wayof example of the embodiment shown in FIG. 37D, “the end position of thelatest user data recording enable range 205” denotes a position thatprecedes point δ. These items of positional information can be describedin ECC block address numbers according to another embodiment instead ofbeing described in physical sector numbers. As described later, in thepresent embodiment, one ECC block is composed of 32 sectors. Therefore,the least significant five bits of the physical sector number of asector arranged at the beginning in a specific ECC block coincides withthat of a sector arranged at the start position in the adjacent ECCblock. In the case where a physical sector number has been assigned sothat the least significant five bits of the physical sector of thesector arranged at the beginning in the ECC block is “00000”, the valuesof the least significant six bits or more of the physical sector numbersof all the sectors existing in the same ECC block coincide with eachother. Therefore, address information obtained by eliminating the leastsignificant five bit data of the physical sector numbers of the sectorsexisting in the same ECC block as above and sampling only data of theleast significant six bit and subsequent is defined as ECC block addressinformation (or ECC block address number). As described later, the datasegment address information (or physical segment block numberinformation recorded in advance by wobble modulation coincides with theabove ECC block address. Thus, when the positional information containedin the recording management data RMD is described in the ECC blockaddress numbers, there is attained advantageous effects described below:

1) An access to an unrecorded area is accelerated in particular:

A differential calculation process is facilitated because a positionalinformation unit of the recording management data RMD coincides with aninformation unit of data segment addresses recorded in advance by wobblemodulation; and

2) A management data size in the recording management data RMD can bereduced:

The number of bits required for describing address information can bereduced by 5 bits per address.

As described later, a single physical segment block length coincideswith a one data segment length, and the user data for one ECC block isrecorded in one data segment. Therefore, an address is expressed as an“ECC block address number”; an “ECC block address”; a “data segmentaddress”, a “data segment number”, or a “physical segment block number”and the like. These expressions have the same meaning.

As shown in FIG. 44, in the allocation position information on therecording management data RMD existing in RMD field 0, size informationin that the recording management zone RMZ capable of sequentiallyadditionally writing the recording management data RMD is recorded inECC block units or in physical segment block units. As shown in FIG. 36(b), one recording management zone RMD is recorded on one by onephysical segment block basis, and thus, based on this information, it ispossible to identify how many times the updated recording managementdata RMD can be additionally written in the recording management zoneRMZ. Next, a current recording management data number is recorded in therecording management zone RMZ. This denotes number information on therecording management data RMD which has been already recorded in therecoding management zone RMZ. For example, assuming that thisinformation corresponds to the information contained in the recordingmanagement data RMD#2 as an example shown in FIG. 36 (b), thisinformation corresponds to the second recorded recording management dataRMD in the recoding management zone RMZ, and thus, a value “2” isrecorded in this field. Next, the residual amount information containedin the recording management zone RMZ is recorded. This informationdenotes information on the item number of the recording management dataRMD which can be further added in the recording management zone RMZ, andis described in physical segment block units (=ECC block units=datasegment units). Among the above three items of information, thefollowing relationship is established.[Size information having set RMZ therein]=[Current recording managementdata number]+[residual amount in RMZ]

The present embodiment is featured in that the use amount or theresidual amount information on the recording management data RMDcontained in the recording management zone RMZ is recorded in arecording area of the recording management data RMD.

For example, in the case where all information is recorded in onewrite-once type information storage medium once, the recordingmanagement data RMD may be recorded only once. However, in the casewhere an attempt is made to repeatedly record additional writing of theuser data (additional writing of the user data in the user dataadditional writing enable range 205 in FIG. 37F) very finely in onewrite-once type information storage medium, it is necessary toadditionally write recording management data RMD updated every timeadditional writing is carried out. In this case, if the recordingmanagement data RMD is frequently additionally written, the reservedarea 273 shown in FIG. 36 (b) is eliminated, and the informationrecording/reproducing apparatus requires countermeasures against thiselimination. Therefore, the use amount or residual amount information onthe recording management data RMD contained in the recording managementzone RMZ is recorded in a recording area of the recording managementdata RMD, thereby making it possible to identify in advance a state inwhich additional writing in the recording management zone RMZ cannot becarried out and to take action by the information recording/reproducingapparatus earlier.

As shown in FIGS. 37E to 37F, the present embodiment is featured in thatthe data lead-out area DTLDO can be set in the form such that theexpanded drive test zone EDRTZ is included (FIG. 1 (E4)). At this time,the start position of the data lead-out area DTLDO changes from point βto point ε. In order to manage this situation, there is provided a fieldfor recording the start position information on the data lead-out areaDTLDO in the allocation position information of the latest (updated)data area DTA of the RMD field shown in FIGS. 44 to 49. As describedpreviously, a drive test (test writing) is basically recorded in clusterunits which can be expanded in data segment (ECC block) units.Therefore, although the start position information on the data lead-outarea DTLDO is described in the ECC block address numbers, thisinformation can be described in the physical sector number or physicalsegment block number, data segment address, or ECC block address of aphysical sector first arranged in this first ECC block according toanother embodiment.

In an RMD field 1, there are recorded: update history information on aninformation recording/reproducing apparatus in which recording of thecorresponding medium has been carried out. This information is describedin accordance with a format of all recording condition informationcontained in information 264 (FIG. 42) in which manufactureridentification information for each information recording/reproducingapparatus; serial numbers and model numbers described in ASCII codes;date and time information when recording power adjustment using a drivetest zone has been made; and recording condition information provided atthe time of additional writing can be set specific to each revision.

An RMD field 2 is a user available area so that a user can recordinformation recorded contents (or contents to be recorded), for example.

The start position information of each border zone BRDZ is recorded inan RMD field 3. That is, as shown in FIG. 45, the start positioninformation from the start to the fiftieth border out areas BTDOs isdescribed in the physical sector numbers.

For example, in the embodiment shown in FIG. 40 (c), the start positionof the first border out area BRDO indicates a position of point η, andthe start position of the second BRDO indicates a position of point θ.

The positional information on an expanded drive test zone is recorded inan RMD field 4. First, there are recorded: the end position informationon a location which has already been used for test writing in the drivetest zone DRTZ which exists in the data lead-in area DTLDI described inFIG. 36 (c); and the end position information on a location which hasalready been used for test writing in the drive test zone DRTZ whichexists in the data lead-out area DTLDO described in FIGS. 37D to 37F. Inthe drive test zone DRTZ, the above position information is sequentiallyused for test writing from the inner periphery side (from the lowestphysical sector number) to the outer periphery direction (in a directionin which the physical sector number is higher). Test writing is carriedout in cluster units which are units of additional writing, as describedlater, and thus, ECC block units are used as location units. Therefore,in the case where the end position information on the location which hasbeen already used for test writing is described in the ECC addressnumbers or is described in the physical sector numbers, there aredescribed a physical sector number of a physical sector arranged at theend of the ECC block which has been used for test writing. Because alocation used for test writing once has already been described, in thecase where next test writing is carried out, such test writing iscarried out from a next of the end position which has already been usedfor test writing. Therefore, the information recording/reproducingapparatus can identify momentarily from where test writing should bestarted by using the end position information (=a use amount in thedrive test zone DRTZ) on a location which has already been used in theabove drive test zone DRTZ. In addition, based on that information, thisapparatus can judge whether or not a free space in which next testwriting can be carried out exists in the drive test zone DRTZ. The drivetest zone DRTZ which exists in the data lead-in area DTLDI records: flaginformation indicating whether or not area size information indicatingthat additional writing can be carried out; flag information indicatingthat this drive test zone DRTZ has been used up or area size informationindicating that additional test writing can be further carried out inthe drive test zone DRTZ which exists in the data lead-out area DLTDI;and area size information indicating that additional test writing canfurther be carried out in the drive test zone DRTZ which exists in thedata lead-out area DTLDO or flag information indicating whether or notthis drive test zone DRTZ has been used up. The size of the drive testzone DRTZ which exists in the data lead-in area DTLDI and the size ofthe drive test zone DRTZ which exists in the data lead-out area DTLDOare identified in advance, thus making it possible to identify the size(residual amount) of an area in which additional test writing can becarried out in the drive test zone DRTZ only based on the end positioninformation on a location which has already been used for test writingin the drive test zone DRTZ which exists in the data lead-in area DTLDIor in the drive test zone DRTZ which exists in the data lead-out areaDTLDO. However, this information is provided in the recording managementdata RMD, thereby making it possible to identify the residual amount inthe drive test zone DRTZ immediately and to reduce a time required forjudging whether or not to newly set the expanded drive test zone EDRTZ.According to another embodiment, in this field, it is possible torecord: flag information indicating whether or not this drive test zoneDRTZ has been used up instead of area size (residual amount) informationindicating that additional writing can further be carried out in thedrive test zone DRTZ. If a flag has already been set to identifymomentarily that the above test zone has already been used up, it ispossible to preclude a danger that test writing is carried out in thisarea.

Additional setting count information on the next expanded drive testzone EDRTZ is recorded in the RMD field 4. In the embodiment shown inFIG. 37E, the expanded drive test zones EDRTZs are set in two zones,i.e., an expanded drive test zone 1 EDRTZ1 and an expanded drive testzone 2 EDRTZ2, and thus, “additional setting count of the expanded drivetest zone EDRTZ=2” is established. Further, range information for eachexpanded drive test zone EDRTZ and range information which has alreadybeen used for test writing are recorded in the RMD field 4. In this way,the positional information on the expanded drive test zone can bemanaged in the recording management data RMD, thereby enabling expansionsetting of the expanded drive test zone EDRTZ a plurality of times. Inaddition, in a write-once type information storage medium, thepositional information on the expanded drive test zone EDRTZ which hasbeen sequentially expanded can be precisely managed in the form ofupdating and additional writing of the recording management data RMD,and it is possible to preclude a danger that the user data isoverwritten on the expanded drive test zone EDRTZ while user dataadditional writing enable range 204 (FIG. 37D) is mistakenly determined.As described above, test writing units are also recorded in clusterunits (ECC block units), and thus, the range of each expanded drive testzone EDRTZ is specified in ECC block address units. In the embodimentshown in FIG. 37E, the start position information on the first setexpanded drive test zone EDRTZ indicates point γ because the expandeddrive test zone 1 EDRTZ1 has been first set; and the end positioninformation on the first set expanded drive test zone EDRTZ correspondsto a position that immediately precedes point β. Positional informationunits are described in the address numbers or physical sector numberssimilarly. While the embodiment of FIGS. 44 and 45 shows the endposition information on the expanded drive test zone EDRTZ, sizeinformation on the expanded drive test zone EDRTZ may be describedwithout being limited thereto. In this case, the size of the first setexpanded drive test zone 1 EDRTZ1 is set to “β-γ”. The end positioninformation on a location which has already been used for test writingin the first set expanded drive test zone EDRTZ is also described withthe ECC block address number or physical sector number. Then, the areasize information (residual amount) in which additional test writing canbe carried out in the first set expanded drive test zone EDRTZ. The sizeof the expanded drive test zone 1 EDRTZ1 and the size of the area, whichhas already been used therein, is already been identified based on theabove described information. Thus, the area size (residual amount) inwhich additional test writing can be carried out is already obtained. Byproviding this field, it is possible to identify immediately whether ornot a current drive test zone will suffice when a new drive test (testwriting) is carried out. In addition, it is possible to reduce ajudgment time required for determining additional setting of a furtherexpanded drive test zone EDRTZ. In this field, there can be recordedarea size (residual amount) information indicating that additionalwriting can be carried out. According to another embodiment, in thisfield it is possible to set flag information indicating whether or notthis expanded drive test zone EDRTZ has been used up. It is possible topreclude a danger that test writing is mistakenly carried out in thisarea, as long as a flag is set to momentarily identify that the testzone has already been used up.

A description will be given with respect to an example of a processingmethod for newly setting an expanded drive test zone EDRTZ by theinformation recording/reproducing apparatus shown in FIG. 11 and carriedout test writing in the zone.

1) A write-once type information storage medium is mounted on aninformation recording/reproducing apparatus.

2) Data formed in the burst cutting area BCA is reproduced by theinformation recording/reproducing unit 141; the recorded data issupplied to the control unit 143; and the information is decoded in thecontrol unit 143, and it is determined whether or not processing canproceeds to a next step.

3) Information recorded in the control data zone CDZ in the systemlead-in area SYLDI is recorded by the information recording/reproducingunit 141, and the reproduced information is transferred to the controlunit 143.

4) Values of rim intensities (in bytes 194 and 195 shown in FIG. 42)when a recommended recording condition has been identified in thecontrol unit 143 are compared with a value of rim intensity of anoptical head used at the information recording/reproducing unit 141; andan area size required for test writing is identified.

5) The information contained in recording management data is reproducedby the information recording/reproducing unit 141, and the reproducedinformation is transferred to the control unit 143. The control sectiondecodes the information contained in the RMD field 4 and determineswhether or not there is a margin of an area size required for testwriting, the size being identified in step 4). In the case where thejudgment result is affirmative, processing proceeds to step 6).Otherwise, processing proceeds to step 9).

6) A location for starting test writing is identified based on endposition information on a location which has already been used for testwriting in the drive test zone DRTZ or expanded drive test zone EDRTZused for test writing from the RMD field 4.

7) Test writing is executed by the size identified in step 4) from thelocation identified in step 6).

8) The number of locations used for test writing has been increased inaccordance with the processing in step 7), and thus, recordingmanagement data RMD obtained by rewriting the end position informationon the locations which has already been used for test writing istemporarily stored in the memory unit 175, and processing proceeds tostep 12).

9) The information recording/reproducing unit 141 reads information on“end position of the latest user data recording enable range 205”recorded in the RMD field 0 or “end position information on the userdata additional writing enable range” recorded in the allocationlocation information on the data area DTA contained in the physicalformed shown in FIG. 43; and the control unit 143 further internallysets the range of a newly set expanded drive test zone EDRTZ.

10) Information on “end position of the latest used data recordingenable range 205” recorded in the RMD field 0 based on the resultdescribed in step 9) is updated and additional setting count informationon the expanded drive test zone EDRTZ contained in the RMD field 4 isincremented by one (that is, the count is added by 1); and further, thememory unit 175 temporarily stores the recording management data RMDobtained by adding the start/end position information on the newly setexpanded drive test zone EDRTZ.

11) Processing moves from step 7) to step 12).

12) Required user information additionally written into the user dataadditional writing enable range 205 under an optimal recording conditionobtained as a result of test writing carried out in step 7).

13) The memory unit 175 temporarily stores the recording management dataRMD updated by additionally writing the start/end position information(FIG. 47) contained in an R zone which has been newly generated inresponse to step 12).

14) The control unit 143 controls the information recording/reproducingunit 141 to additionally record the latest recording management data RMDtemporarily stored in the memory unit 175, in the reserved area 273 (forexample, FIG. 36 (b)) contained in the recording management zone RMZ.

As shown in FIG. 47, positional information on the expanded spare areaESPA is recorded in an RMD field 5. In the write-once type informationstorage medium, a spare area can be expanded, and the positionalinformation on that spare area is managed in the position managementdata RMD. In the embodiment shown in FIG. 37E, the expanded spare areaESPA is set in two areas, i.e., an expanded spare area 1 ESPA1 and anexpanded spare area 2 ESPA2, and thus, “the number of additionalsettings of the expanded space area ESPA” is set to “2”. The startposition information on the first set expanded spare area ESPAcorresponds to at a position of point δ; the end position information onthe second set expanded spare area ESPA corresponds to at a positionthat precedes point γ; the end position information on the first setexpanded spare area ESPA corresponds to at a position that precedespoint ξ; and the end position information on the second set expandedspare area ESPA corresponds to at a position of point ε.

The information relating to defect management is recorded in the RMDfield 5 shown in FIG. 47. A first field in the RMD field 5 shown in FIG.47 records ECC block number information or physical segment block numberinformation which has already been used for substitution in the adjacentarea to the data lead-in area DTLDI. In the present embodiment, asubstituting process is carried out in ECC block units with respect to adefect area found in the user data additional writing range 204. Asdescribed later, one data segment configuring one ECC block is recordedin one physical segment block area, and thus, the substitution countwhich has already been done is equal to the number of ECC blocks whichhas already been used (or number of physical segment blocks and numberof data segments). Therefore, the units of information described in thisfield are obtained as ECC block units or physical segment block unitsand data segment units. In the write-once type information storagemedium, in the spare area SPA or expanded pare area ESPA, a locationused as a replacing process may be often used sequentially from theinner periphery side having the lowest ECC block address number.Therefore, with respect to the information contained in this field, inanother embodiment, it is possible to describe an ECC block addressnumber as the end position information on a location which has alreadybeen used for substitution. As shown in FIG. 47, with respect to thefirst set expanded spare area 1 ESPA1 and the second set expanded sparearea 2 ESPA2 as well, there exist fields for recording similarinformation (“ECC block number information or physical segment blocknumber information which have already been used for substitution in thefirst set expanded spare area ESPA or end position information (ECCblock address number) on a location which has been used forsubstitution”; and “ECC block number information or physical segmentblock number information which have already been used for substitutionin the second set expanded spare area ESPA or end position information(ECC block address number) on a location which has been used forsubstitution”.

Using these items of information, the following advantageous effects areattained:

1) A spare location to be newly set with respect to a defect area foundin the user data additional writing enable range 205 is identifiedimmediately when next substituting process is carried out.

New substitution is carried out immediately after the end position of alocation which has already been used for substitution.

2) The residual amount in the spare area SPA or expanded spare area ESPAis obtained by calculation and (in the case where the residual amount isinsufficient), it is possible to identify necessity of setting a newexpanded spare area ESPA.

The size of the spare area SPA adjacent to the data lead-in area DTLDIis identified in advance, and thus, the residual amount in the sparearea SPA can be calculated if there exists information relating to thenumber of ECC blocks which have already been used in the spare area SPA.However, the residual amount can be identified immediately by providinga recording frame of the ECC block number information or physicalsegment block number information in an unused location available forfuture substitution, which is residual amount information contained inthe spare area SPA. Thus, it is possible to reduce a time required forjudgment of the necessity of providing settings relating to a furtherexpanded spare area ESPA. For a similar reason, there is provided aframe capable of recording “residual amount information contained in thefirst set expanded spare area ESPA and “residual amount informationcontained in the second set expanded spare area ESPA. In the presentembodiment, a spare area SPA is extensible in the write-once typeinformation storage medium, and the associated position information ismanaged in the recording management data RMD. As shown in FIGS. 37A to37F, it is possible to extensively set an expanded spare area 1 ESPA1and an expanded spare area 2 ESPA2 or the like at an arbitrary startposition and at an arbitrary size as required in the user dataadditional writing enable range 204. Therefore, the additional settingcount information on the expanded spare area ESPA is recorded in the RMDfield 5, making it possible to set the start position information on thefirst set expanded spare area ESPA or the start position information onthe secondly set expanded spare area ESPA. These items of start positioninformation are described in physical sector numbers or ECC blockaddress numbers (or physical segment block numbers or data segmentaddresses). In the embodiment shown in FIGS. 44 and 45, “the endposition information on the first set expanded spare area ESPA” or “theend position information on the second set expanded spare area ESPA” arerecorded as information for specifying the range of the expanded sparearea ESPA. However, in another embodiment, in stead of these items ofend position information, size information on the expanded spare areaESPA can be recorded by the ECC block number or physical segment blocknumber, data segment number, and ECC block number or physical sectornumber.

Defect management information is recorded in an RMD field 6. The presentembodiment uses a method for improving reliability of information to berecorded in an information storage medium, the information relating todefect processing, in the following two modes:

1) A conventional “replacing mode” for recording in a spare locationinformation to be recorded in a defect location; and

2) A “multiplying mode” for recording the same contents of informationtwice in a location which is different from another one on aninformation storage medium, thereby improving reliability.

Information as to which mode processing is carried out is recorded in“type information on defect management processing” contained insecondary defect list entry information contained in the recordingmanagement data RMD as shown in FIG. 48. The contents of secondarydefect list entry information are as follows:

1) In the case of the conventional replacing mode

Type information on defect management processing is set to “01” (in thesame manner as in conventional DVD-RAM);

The “positional information on a replacement source ECC block” used heredenotes positional information on an ECC block found as a defectlocation in the user data additional writing enable range 205, andinformation to be essentially recorded-in the range is recorded in aspare area or the like without being recorded in the above range; and

The “positional information on a replacement destination ECC block” usedhere indicates positional information on a location of a replacementsource to be set in the spare area SPA or expanded spare area 1 ESPA1,and an expanded spare area 2 ESPA2 shown in FIG. 37E, and theinformation to be recorded in a defect location, the information beingfound in the additional writing enable range 205, is recorded in theabove area.

2) In the case of the multiplying mode

Type information on defect management processing is set to “10”;

The “positional information on replacement source ECC block” denotes anon-defect location, and indicates position information in which targetinformation is recorded and the information recorded therein can beprecisely reproduced; and

The “positional information on replacement destination ECC block”indicates positional information on a location in which the completelysame contents as the information recorded in the above described“positional information on replacement source ECC block” are recordedfor the purpose of multiplication set in the spare area SPA or expandedspare area 1 ESPA1 and expanded spare area 2 ESPA 2 shown in FIG. 37E.

In the case where recording has been carried out in the above described“1) conventional replacing mode”, it is confirmed that the informationrecorded in an information storage medium is precisely read out at thestage immediately after recording. However, there is a danger that theabove described information cannot be reproduced due to scratch or dustadhering to an information storage medium, caused by the user's abuse.In contrast, in the case where recording has been carried out in the “2)multiplying mode”, even if information cannot be partially read in aninformation storage medium due to a scratch or dust caused by user'sabuse or the like, because the same information is backed up at anotherportion, the reliability of information reproduction is remarkablyimproved. The above backed up information is utilized for theinformation which cannot be read at this time, and the replacing processin “1) conventional replacing mode” is carried out, thereby furtherimproving reliability. Therefore, there is attained advantageous effectthat high reliability of information reproduction after recorded,considering countermeasures against scratch or dust can be arranged by aprocessing operation in “1) conventional replacing mode” alone and byusing a combination of the processing operation in “1) conventionalreplacing mode” and a processing mode in “2) multiplying mode”. Methodsfor describing the positional information on the above ECC blockinclude: a method for describing a physical sector number of a physicalsector which exists at a start position which configures the above ECCblock and a method for describing an ECC block address, a physicalsegment block address, or a data segment address. As described later, inthe present embodiment, a data area including data of one ECC block sizeis referred to as a data segment. A physical segment block is defined asa physical unit on an information storage medium serving as a locationfor recording data, and one physical segment size coincides with a sizeof an area for recording one data segment.

The present embodiment provides a mechanism capable of recording thedefect position information detected in advance before the replacingprocess. In this manner, the manufacturers of information storagemediums check a defect state in the user data additional writing range204 immediately before shipment. When the detected defect location isrecorded in advance (before the replacing process) or the informationrecording/reproducing apparatus has carried out an initializing processat the user's site, the defect state in the user data additional writingenable range 294 is checked so that the detected defect location can berecorded in advance (before the replacing process). In this way, theinformation indicating a defect position detected in advance before thereplacing process corresponds to “information on the presence or absenceof the process for replacing a defect block with a spare block” (SLR:State of Linear Replacement) contained in the secondary defect listentry information.

When the information SLR on the presence or absence of the process forreplacing a defect block with a spare block is set to “0”:

The replacing process is carried out with respect to a defect ECC blockspecified by “positional information on replacement source ECC block”;and

Information, which can be reproduced, is recorded in a locationspecified by “positional information on replacement destination ECCblock”.

When the information SLR on the presence or absence of the process forreplacing a defect block with a spare block is set to “1”:

A defect ECC block specified by “positional information on replacementsource ECC block” denotes a defect block detected in advance at thestate that precedes the replacing process; and

A field of “positional information on replacement destination ECC block”is blanked (no information is recorded).

When a defect location is thus identified in advance, there is attainedadvantageous effect that an optimal replacing process can be carried outat a high speed (and in a real time) at the stage at which aninformation recording/reproducing apparatus carries out additionalwriting in a write-once type information storage medium. In addition, inthe case where video image information or the like is recorded in theinformation storage medium, it is necessary to guarantee continuity atthe time of recording, and a high speed replacing process based on theabove described information becomes important.

If a defect occurs in the user data additional writing enable range 205,the replacing process is carried out in predetermined location placed inthe spare area SPA or expanded spare area ESPA. Every time the replacingprocess is carried out, one item of Secondary Defect List Entryinformation is added; and set information on the positional informationon an ECC block utilized as a substitute of the positional informationon a defect ECC block is recorded in this RMD field 6. When additionalwriting of the user data is newly repeated in the user data additionalwriting enable range 205, if a new defect location is detected, thereplacing process is carried out, and the number of items of thesecondary defect list entry information increases. A managementinformation area (RMD field 6) for defect management can be expanded byadditionally writing the recording management data RMD with an increasednumber of items of this Secondary Defect List Entry information into thereserved area 273 contained in the recording management zone RMZ, asshown in FIG. 36 (b). By using this method, the reliability of defectmanagement information itself can be improved for the reasons describedbelow.

1) The recording management data RMD can be recorded while avoiding adefect location in the recording management zone RMZ.

A defect location may be produced in the recording management zone RMZshown in FIG. 36 (b). The contents of the recording management data RMDnewly additionally written in the recording management zone RMZ areverified immediately after additional writing, thereby making itpossible to sense a state in which recording cannot be carried out dueto a defect. In that case, the recording management data RMD isrewritten adjacent to the defect location, thereby making it possible torecord the recording management data RMD in the form such that highreliability is guaranteed.

2) Even if the past recording management data RMD cannot be reproduceddue to the scratch adhering to an information storage medium surface, acertain degree of backup can be carried out.

For example, in the case where the example shown in FIG. 36 (b) istaken, a state in which, after recording management data RMD#2 has beenrecorded, the information storage medium surface is scratched due to theuser's mistake or the like, and then, the recording management dataRMD#2 cannot be reproduced, is presumed as an example. In this case, acertain degree of the past defect management information (informationcontained in the RMD field 6) can be recovered by reproducinginformation on the recording management data RMD#1 instead.

Size information on the RMD field 6 is recorded at the beginning of theRMD field 6, and this field size is made variable, thereby making itpossible to expand the management information area (RMD field 6) fordefect management. Each RMD field is set to 2048 size (for one physicalsector size), as described previously. However, if a plenty of defectsoccur with the information storage medium, and then, the replacingprocess count increases, the size of the Secondary Detect Listinformation increases, and the 2048 byte size (for one physical sectorsize) becomes insufficient. In consideration of this situation, the RMDfield 6 can be set to a plurality of multiples of 2048 size (recordingacross a plurality of sectors can be carried out). Namely, if “the sizeof the RMD field 6” has exceeded 2048 bytes, an area for a plurality ofphysical sectors is arranged to the RMD field 6.

The secondary defect list information SDL records: the secondary defectlist entry information described above; “secondary defect listidentification information” indicating a start position of the secondarydefect list information SDL; and “secondary defect list update counter(update count information)” indicating count information as to how manytimes the secondary defect list information SDL has been rewritten. Thedata size of the whole secondary defect list information SDL can beidentified based on “number information on the secondary defect listentry”.

As described previously, user data recording is locally carried out inunits of R zone in the user data additional writing enable range 205.That is, part of the user data additional writing enable range 205reserved for recoding the user data is referred to as an R zone. This Rzone is divided into two types according to a recording condition. Amongthem, a type of zone in which additional user data can be furtherrecorded is referred to as an Open R Zone, and a type of zone in whichno further user data can be added is referred to as a Complete R Zone.The user data additionally writing enable range 205 cannot have three ormore Open R zones. That is, up to two Open R zones can be set in theuser data additional writing enable range 205. A location in whicheither of the above two types of R zones are not set in the user dataadditional writing enable range 205, i.e., a location in which the userdata is reserved to record the user data (as either of the above twotypes of R zones), is referred to as an unspecified R zone (Invisible RZone). In the case where the user data is fully recorded in the userdata additional writing enable range 205, and then, no data can beadded, this Invisible R zone does not exist. Up to 254-th R zoneposition information is recorded in an RMD field 7. The “whole R zonenumber information” first recorded in the RMD field 7 denotes a totalnumber totalizing the number of Invisible R Zone logically establishedin the user data additional writing enable range 205, Open R Zones andthe number of Complete R Zones. Next, the number information on thefirst Open R zone and the number information on the second Open R zonesare recorded. As described previously, the user data additional writingenable range 205 cannot have three or more Open R zones, and thus, “1”or “0” is recorded (in the case where the first or second Open R zonedoes not exist). Next, the start position information and the endposition information on the first Complete R zone are described inphysical sector numbers. Then, the second to 254th start positioninformation and end position information are sequentially described inthe physical sector numbers.

In an RMD field 8 and subsequent, the 255-th and subsequent startposition information and end position information are sequentiallydescribed in the physical sector numbers, and a maximum of RMD fields 15(a maximum of 2047 Complete R zones) can be described according to thenumber of Complete R Zones.

FIGS. 51 and 52 each show another embodiment with respect to a datastructure in the recording management data RMD shown in FIGS. 44 to 49.

In the embodiment shown in FIGS. 51 and 52, up to 128 bordered areasBRDAs can be set on one write-once type information storage medium.Therefore, the start position information on the first to 128 border outareas BRDOs is recorded in the RMD field 3. In the case where (128 orless) bordered areas BRDAs are set midway, “00h” is set as the startposition information on the subsequent border out areas BRDOs. In thismanner, it is possible to identify how many bordered areas BRDAs are seton the write-once information storage medium merely by checking to wherethe start position information on the border out areas BRDOs arerecorded in the RMD field 3.

In the embodiment shown in FIGS. 51 and 52, up to 128 expanded recordingmanagement zones RMZs can be set on one write-once information storagemedium. As described above, there are two types of expanded recordingmanagement zones RMZs such as:

1) an expanded recording management zone RMZ set in the border-in areaBRDI; and

2) an expanded recording management zone RMZ set by utilizing an R zone.

In the embodiment shown in FIGS. 51 and 52, without discriminating thesetwo types of RMZ zones, they are managed by recoding a pair of the startposition information on the expanded recording management zone RMZ(indicated by the physical sector number) and size information (numberinformation on occupying physical sectors) in the RMD field 3. In theembodiment shown in FIGS. 51 and 52, although there has been recorded:information on a pair of the start position information (indicated bythe physical sector number) and size information (number information onoccupying physical sectors) on the expanded recording management zoneRMZ, a set of the start position (indicated by the physical sectornumber) and the end position information (indicated by the physicalsector number) on the expanded recording management zone RMZ may berecorded without being limited thereto. In the embodiment shown in FIGS.51 and 52, although the expanded recording management zones RMZ numbershave been assigned in order set on the write-once type informationstorage medium, the expanded recording management data zone RMZ numberscan be assigned in order from the lowest physical sector number as astart position without being limited thereto. Then, the latest recordingmanagement data RMD is recorded, a currently used recording managementzone (which is open to enable additional writing of RMD) is specified bythe number of this expanded recording management zone RMZ. Therefore,the information recording/reproducing apparatus or the informationreproducing apparatus identifies the start position information on thecurrently used (opened so that the RMZ can be additionally recorded)recording management zone based on these items of information, andcarries out identification of which one is the latest recordingmanagement data RMD from the identified information. Even if theexpanded recording management zone is arranged to be distributed ontothe write-once type information storage medium, the informationrecording/reproducing apparatus or information reproducing apparatus caneasily carry out identification of which one is the latest recordingmanagement data RMD by taking a data structure shown in FIGS. 51 and 52each. Based on these items of information; the start positioninformation on the currently used (opened) recording management zone isidentified; and the location is accessed to identify to where therecording management data RMD has already been recorded. In this manner,the information recording/reproducing apparatus or the informationreproducing apparatus can easily identify to where the updated latestrecording management data may be recorded.

In the case where 2) an expanded recording management zone RMZ set byutilizing an R zone has been set, one whole R zone corresponds to oneexpanded recording management zone RMZ. Thus, the physical sector numberindicating the corresponding start position of the expanded recordingmanagement zone RMZ described in the RMD field 3 coincides with thecorresponding physical sector number indicating the start position ofthe R zone described in the RMD fields 4 to 21.

In the embodiment shown in FIGS. 51 and 52, up to 4606 (4351+255) Rzones can be set in one write-once type information storage medium. Thisset R zone position information is recorded in the RMD field 4 to 21.The start position information on each R zone is displayed by theinformation on the physical sector number, and the physical sectornumbers LRAs (Last Recorded Addresses) indicating the end recordingposition in each R zone are recorded in pair. Although the R zonesdescribed in the recording management data RMD are set in order ofsetting R zones in the embodiment shown in FIGS. 51 and 52, these zonescan be set in order from the lowest physical sector number indicatingthe start position information without being limited thereto. In thecase where R zone setting of the corresponding number is not provided,“00h” is recorded in this field. Number information on invisible R zoneis described in the RMD field 4. This number information on invisible Rzone is indicated by a total number of the number of invisible R zones(zones in which area reserved for data recording is not made in dataarea DTA); the number of open type R zones (zones each having anunrecorded area in which additional writing can be carried out); and thenumber of complete type R zones (R zones which are already complete andwhich does not have an unrecorded area in which additional writing canbe carried out). In the embodiment shown in FIGS. 51 and 52, it ispossible to set up to two Open R zones in which additional writing canbe carried out. In this way, by setting up to two Open R zones, it ispossible to record video image information or audio information forwhich continuous recording or continuous reproduction must be guaranteedin one Open R zone, and then, separately record management informationrelevant to the video image information or audio information; generalinformation used by a personal computer or the like; or file systemmanagement information in the remaining one Open R zone. Namely, it ispossible to separately record plural items of information in anotherOpen R zone according to type of user data to be recorded. This resultsin improved convenience in recording or reproducing AV information(video image information or audio information). In the embodiment shownin FIGS. 51 and 52, which R zone is an Open R zone is specified by the Rzone allocation numbers arranged in the RMD fields 4 to 21. That is, theR zones are specified by the corresponding R zone number to the firstand second Open R zones. A search can be easily made for the Open R zoneby taking such a data structure. In the case where no Open R zoneexists, “00h” is recorded in that field. In the present embodiment, theend position of an R zone coincides with the end recording position inthe Complete R zone, the end position of the R zone and the lastrecording position LRA in the R zone are different from each other inthe Open T zone. On the way of additionally writing user information inthe Open R zone (at a state that precedes completion of additionalwriting of the recording management data RMD to be updated), the endrecording position and a recording position at which additional writingcan be further carried out are shifted. However, after an additionalwriting process of user information has completed, after completing theadditional writing process of the latest recording management data RMDto be recorded, the end recording position and an end recording positionat which additional writing can be further carried out coincide witheach other. Therefore, after completing the additional writing processof the latest recording management data RMD to be updated, in the casewhere additional writing of new user data is carried out, the controlunit 143 in the information recording/reproducing apparatus shown inFIG. 11 carries out processing in accordance with procedures for:

1) checking a number of an R zone which corresponds to the Open R zonedescribed in the RMD field 4;

2) checking a physical sector number indicating an end recordingposition in the Open R zone described in each of the RMD fields 4 to 21to identify an end recording position at which additional writing can becarried out; and

3) starting additional writing from the above identified end recordingposition NWA at which additional writing can be carried out.

In this manner, a new additional writing start position is identified byutilizing Open R zone information in the RMD field 4, thereby making itpossible to sample a new additional writing start position simply andspeedily.

FIG. 53 shows a data structure in an RMD field in the embodiment shownin FIGS. 51 and 52. As compared with the embodiment shown in FIGS. 44 to49, there are added: address information on a location in whichrecording condition adjustment has been made in the inner drive testzone DRTZ (which belongs to the data lead-in area DTLDI); and addressinformation on a location in which recording condition adjustment hasbeen made in the outer drive test zone DRTZ (which belongs to the datalead-out area DTLDO). These items of information are described in thephysical segment block address numbers. Further, in the embodiment shownin FIG. 53, there are added: information relating to a method forautomatically adjusting a recording condition (running OPC); and the endDSV (Digital Sum Value) value at the end of recording.

FIG. 56 shows an outline of converting procedures for, after an ECCblock is configured of a data frame structure in which user data inunits of 2048 bytes has been recorded, and then, sync codes have beenadded, forming a physical sector structure to be recorded in aninformation storage medium. These converting procedures are employed incommon for a read-only type information storage medium, a write-oncetype information storage medium, and a rewritable-type informationstorage medium. According to each converting stage, a data frame, ascrambled frame, a recording flame, or recorded data field are defined.The data frame is a location in which user data is recorded. This frameis composed of: main data consisting of 2048 types; a four-type data ID;a two-byte ID error detecting code (IED); a six-byte reserved bytes(RSV); and a four-byte error detecting code (EDC). First, after an IED(ID error detecting code) has been added to a data ID described later,the 6-byte reserved byte and main data consisting of 2048 bytes and inwhich the user data is recorded are added. Then, an error detecting code(EDC) is added. Then, scrambling relevant to the main data is executed.Here, a Cross Reed-Solomon Error Correction Code is applied to thesescrambled 32 data frames (scrambled frames), and an ECC encodeprocessing operation is executed. In this manner, a recording frame isconfigured. This recording frame includes a parity of outer-code (PO)and a parity of inner-code (PI). The PO and PI each are error correctingcodes produced with respect ECC blocks, each of which is formed of 32scrambled frames. The recording frame, as described previously, issubjected to ETM (Eight to Twelve Modulation) for converting eight databits to 12-channel bits. Then, a sync code SYNC is added to thebeginning on a 91 by 91 bytes basis, and 32 physical sectors are formed.As described in the lower right (frame shown in FIG. 56, the presentembodiment is featured in that one error correcting unit (ECC block) iscomposed of 32 sectors. As described later, the numbers “0” to 31” ineach frame shown in FIG. 60 or 61 indicate the numbers of physicalsectors, respectively, and a structure is provided to ensure that onelarge ECC block is composed of a total of 32 physical sectors. In anext-generation DVD, even in the case where a scratch whose extent isidentical to that of a current-generation DVD adheres to an informationstorage medium surface, it is required to enable reproduction of preciseinformation by an error correction processing operation. In the presentembodiment, recording density has been improved for the achievement ofhigh capacity. As a result, in the case where a conventional one ECCblock=16 sectors, a length of a physical scratch which can be correctedby error correction is reduced as compared with a conventional DVD. Asin the present embodiment, there is attained advantageous effect thatone ECC block is composed of 32 sectors, thereby making it possible toincrease an allowable length of a scratch on the information storagemedium surface for which error correction can be carried out and toensure compatibility/format continuity of a current DVD ECC blockstructure.

FIG. 57 shows a structure in a data frame. One data frame is 2064 bytesconsisting of 172 bytes×2×6 rows, and includes main data of 2048 bytes.IED is an acronym for IE Error Detection Code, and denotes a reservedarea for enabling setting of information in the future. EDC is anacronym for Error Detection Code, and denotes an additional code forerror detection of a whole data frame.

FIG. 50 shows a data structure in a data ID shown in FIG. 57. The dataID is composed of items of information on data frames 921 and 922. Thedata frame number indicates a physical sector number 922 of thecorresponding data frame.

The data frame information 921 is composed of the following items ofinformation.

Format Type 931

-   -   0b: This indicates CLV    -   1b: This indicates zone configuration

Tracking Method 932

-   -   0b: This is pit-compatible and uses a DPD (Differential Phase        Detect) technique in the present embodiment    -   1b: This is pre-groove compatible and uses a push-pull technique        or a DPP (Differential Push-Pull) technique.

Recording Film Reflection Factor 933

-   -   0b: 40% or more    -   1b: 40% or less

Recording Type Information 934

-   -   0b: General data    -   1b: Real time data (Audio Video data)

Area Type Information 935

-   -   00b: Data area DTA    -   01b: System lead-in area SYLDI or data lead-in area DTLDI    -   10b: Data lead-out area DTLDO or system lead-out area SYLDO

Data Type Information 936

-   -   0b: Read-only data    -   1b: Rewritable data

Layer Number 937

-   -   0b: Layer 0    -   1b: Layer 1

FIG. 58A shows an example of default values assigned to a feedback shiftregister when a frame after scrambled is produced. FIG. 58B shows acircuit configuration of the feedback shift register for producingscrambled bytes. The values of r7 (MSB) to r0 (LSB) are used as scramblebytes while they are shifted by 8 by 8 bit basis. As shown in FIG. 58A,16 types of preset values are provided in the present embodiment. Thedefault preset numbers shown in FIG. 58A are equal to 4 bits of data ID(b7 (MSB) to b4 (LSB)). When data frame scrambling is started, thedefault values of r14 to r0 must be set to the default preset values ina table shown in FIG. 58A. The same default preset value is used for 16continuous data frames. Next, the default preset values are changed, andthe changed same preset value is used for the 16 continuous data frames.

The least significant eight bits of the default values of r7 to r0 aresampled as a scramble byte S0. Then, eight-bit shifting is carried out,and the scrambled byte is then sampled. Such an operation is repeated2047 times.

FIG. 59 shows an ECC block structure in the present embodiment. The ECCblock is formed of 32 scrambled frames. 192 rows+16 rows are arranged ina vertical direction, and (172+10)×2 columns are arranged in ahorizontal direction. B_(0,0), B_(1,0), . . . are one byte,respectively. PO and PI are error correction codes, and an outer parityand an inner parity. In the present embodiment, an ECC block structureusing a multiple code is configured. That is, as error correctionadditional bits, a structure is provided such that, PI (Parity in) isadded in a “row” direction, and PO (Parity out) is added in a “column”direction. A high error correction capability using an erasurecorrection and a vertical and horizontal repetitive correction processcan be guaranteed by configuring such an ECC block structure using amultiple code. Unlike a conventional DVD ECC block structure, the ECCblock structure shown in FIG. 59 is featured in that two PIs are set inthe same “row”. That is, PI of 10-byte size described at the center inFIG. 59 is added to 172 bytes arranged at the left side. That is, forexample, 10-byte PI from B_(0,0) to B_(0,172) is added to 172-byte datafrom B_(0,0) to B_(0,171); and 10-byte PI from B_(1,172) to B_(1,181) isadded to 172-byte data from B_(1,0) to B_(1,171). The PI of 10-byte sizedescribed at the right end of FIG. 59 is added to 172 bytes arranged atthe center on the left side of the FIG. 59. That is, for example,10-byte PI from B_(0,354) to B_(0,363) are added to 172-byte data fromB_(0,182) to B_(0,353.)

FIG. 60 shows an illustration of a frame arrangement after scrambled.Units of (6 rows×172 bytes) are handled as one frame after scrambled.That is, one ECC block is formed of 32 frames after scrambled. Further,this system handles a pair of (block 182 bytes×207 bytes). When L isassigned to the number of each frame after scrambled, in the left sideECC block, and R is assigned to the number of each frame after scrambledin the right side ECC block, the frames after scrambled are arranged asshown in FIG. 60. That is, the left and right frames after scrambledexist alternately at the left side block, and the frames after scrambledexist alternately at the right side block.

That is, the ECC block is formed of 32 frames after continuouslyscrambled. Lines of the left half of odd numbered sectors each areexchanged with those of the right half. 172×2 bytes×192 rows are equalto 172 bytes×12 rows×32 scrambled frames, and are obtained as a dataarea. 16-byte PO is added to form an outer code of RS (208, 192, 17) ineach 172×2 columns. 10-byte PI (RS (182, 172, 11)) is added to each208×2 rows in the left and right blocks. PI is added to a row of PO aswell. The numerals in frames indicate scrambled frame numbers, andsuffixes R and L denote the right half and the left half of thescrambled frame. The present embodiment is featured in that the samedata frame is arranged to be distributed in a plurality of small ECCblocks. Specifically, in the present embodiment, a large one ECC blockis composed of two small ECC blocks, and the same data frame arearranged to be alternately distributed into two small ECC blocks. As hasalready been described in FIG. 59, PI of 10-byte size described at thecenter is added to 172 bytes arranged at the left side, and PI of 10byte size described on the right end is added to 172 bytes arranged atthe center on the left side. Namely, the left side small ECC block iscomposed of continuous PI of 10 bytes from the left end of FIG. 59, andthe right side small ECC block is composed of 10 bytes at the right endfrom the central 172 bytes. The signs in each frame are set in responseto these blocks in FIG. 60. For example, “2-R” denotes which of a dataframe number and the left and right small ECC blocks one belongs to (forexample, one belongs to right side small ECC block in second dataframe). As described later, with respect to each of the finallyconfigured physical sectors, the data contained in the same physicalsector is also alternately arranged to be distributed into the left andright small ECC blocks (the columns of the left half in FIG. 61 areincluded in the left side small ECC block (small ECC block “A” on theleft side shown in FIG. 64), and the column of the right half areincluded in small ECC blocks (small ECC block B on the right side shownin FIG. 64).

Thus, when the same data frame is arranged to be distributed in aplurality of small ECC blocks, the reliability of recording data isimproved by improving an error correction capability of the datacontained in a physical sector (FIG. 61). For example, let us consider acase in which a track fails at the time of recording; the recorded datais overwritten; and data for one physical sector is damaged. In thepresent embodiment, the damaged data contained in one sector issubjected to error correction by using two small ECC blocks; a burden onerror correction in one ECC block is reduced; and error correction withbetter performance is guaranteed. In the present embodiment, even afterforming an ECC block, a structure is provided such that a data ID isarranged at the start position of each sector, thus making it possibleto check a data position at the time of access at a high speed.

FIG. 61 shows an illustration of a PO interleaving method. As shown inFIG. 61, 16 parities are distributed on one by one row basis. That is,16 parity rows are arranged on a one by one row basis with respect totwo recording frames placed. Therefore, a recording fame consisting of12 rows is obtained as 12 rows+1 row. After this row interleaving hasbeen carried out, 13 rows×182 bytes are referred to as a recordingframe. Therefore, an ECC block after row interleaved is formed of 32recording frames. In one recording, as described in FIG. 60, 6 rowsexist in each of the right side and left side blocks. POs are arrangedso as to be positioned in different rows between a left block (182×208bytes) and a right block (182×208 bytes). FIG. 61 shows one completetype ECC block. However, at the time of actual data reproduction, suchECC blocks continuously arrive at an error correction processingsection. In order to improve such an error correction processingcapability, there is employed an interleaving system as shown in FIG.61.

Referring to FIG. 61, a detailed description will be given with respectto a relationship from a structure in one data frame shown in FIG. 57 toa PO interleaving method shown in FIG. 61. FIG. 64 is an enlarged viewshowing, an upper side portion of an EC block structure afterPO-interleaved shown in FIG. 61, wherein allocation locations of dataID, IED, RSV, and EDC shown in FIG. 57 are explicitly indicated, therebyvisually identifying a series of conversion from FIGS. 57 to 61. “0-L”“0-R”, “1-R”, and “1-L” shown in FIG. 64 correspond to “0-L”, “0-R”,“1-R”, and “1-L” shown in FIG. 60, respectively. The “0-L” and “1-L”denote data obtained after only the main data has been scrambled withrespect to the left half shown in FIG. 57, that is, a set composed of172 bytes and six rows from the center line to the left side. Similarly,the “0-R” and “1-R” denote data obtained after only the main data hasbeen scrambled with respect to the right half shown in FIG. 57, that is,a set composed of 172 bytes and six rows from the center line to theright side. Therefore, as is evident from FIG. 57, data ID, IED, and RSVare arranged in order from the beginning of the first row (row 0) tobyte 12 of “0-L” and “1-L”. In FIG. 64, the centerline to the left sideconfigures the left side small ECC block “A”, and the centerline to theright side configures the right side small ECC block “B”. Therefore, asis evident from FIG. 64, data ID#1, data ID#2, IED#0, IED#2, RSV#0, andRSV#2 included in “0-L” and “2-L” are included in the left side smallECC block “A”. In FIG. 60, “0-L” and “2-L” are arranged at the leftside, and “0-R” and “2-E” are arranged at the right side. In contrast,“1-R” and “1-L” are arranged at the left and right sides, respectively.Data ID#1, IED#1, and RSV#1 are arranged from the beginning to byte 12of the first row in “1-L”. Thus, as a result of reversing the left andright allocations, as is evident from FIG. 64, data ID#1, IED#1, andRSV#1 included in “1-L” is configured in the right side small ECC block“B”. In the present embodiment, a combination of “0-L” and “0-R” in FIG.64 is referred to as a “0-th recording frame” and a combination of “1-L”and “1-R” is referred to as a “first recording frame”. The boundarybetween the recording frames are indicated by the bold characters shownin FIG. 64. As is evident from FIG. 64, data ID is arranged at thebeginning of each recording frame and PO and PI-L are arranged at theend of each recording frame. As shown in FIG. 64, the present embodimentis featured in that small ECC blocks in which data ID is included aredifferent from each other depending on the odd-numbered andeven-numbered recording frames, and data ID, IED, and RSV arealternately arranged in the left side and right side small ECC blocks“A” and “B” in accordance with continuous recording frames. The errorcorrection capability in one small ECC lock is limited, and errorcorrection is disabled with respect to a random error exceeding aspecific number or a burst error exceeding a specific length. Asdescribed above, data ID, IED, and RSV are alternately arranged in theleft side and right side small ECC blocks “A” and “B”, thereby making itpossible to improve the reliability of reproduction of data ID. That is,even if a defect on an information storage medium frequently occurs,disabling error correction of any of the small ECC blocks and disablingdecoding of data ID to which the faulty block belongs, data ID, IED, andRSV are alternately arranged in the left side and right side small ECCblocks “A” and “B”, thus enabling error correction in the other smallECC block and enabling decoding the remaining data ID. Because theaddress information contained in data ID continuously lasts, theinformation on data ID is used, enabling interpolation with respect tothe information on data ID which has not been successfully decoded. As aresult, the access reliability can be improved according to theembodiment shown in FIG. 64. The numbers parenthesized at the left sideof FIG. 64 denote row numbers in an ECC block after PO-interleaved. Inthe case where numbers are recorded in an information storage medium,row numbers are sequentially recorded from the left to the right. InFIG. 64, data ID intervals included in each recording frame are alwaysconstantly arranged, and thus, there is attained advantageous effectthat data ID position searching capability is improved.

A physical sector structure is shown in FIGS. 62A and 62B. FIG. 62Ashows an even numbered physical sector structure, and FIG. 62B show anodd numbered data structure. In FIGS. 62A and 62B, with respect to bothof an even recorded data field and an odd recorded data field, outerparity PO information shown in FIG. 61 is inserted into a sync data areacontained in the last 2 sync frames (i.e., in a portion at which thelast sync code is SY3 and a portion at which the immediately succeedingsync data and sync code is SY1; and a portion at which sync code is SY1and a portion at which the immediately succeeding sync data is arrangedin the sync data area shown in FIG. 61 wherein information of outerparity PO is inserted).

Part of the left side PO shown in FIG. 60 is inserted at the last twosync frames in the even recorded data field, and part of the right sidePO shown in FIG. 60 is inserted at the last two sync frames in the oddrecorded data field. As shown in FIG. 60, one ECC block is composed ofthe left and right small ECC blocks, respectively, and the data on POgroups alternately different depending on sectors (the data on PObelonging to left small ECC block or the data on PO belonging to rightsmall ECC block) is inserted. The even numbered physical sectorstructure shown in FIG. 62A and the odd numbered data structure shown inFIG. 62B are divided into two sections at a center line. The left side“24+1092+24+1092 channel bits are included in the left side small ECCblock shown in FIG. 59 or 60, and the right side “24+1092+24+1092channel bits are included in the right side small ECC block shown inFIG. 59 or 60. In the case where the physical sector structure shown inFIGS. 62A and 62B is recorded in an information storage medium, thisstructure is serially recorded on one by one column base. Therefore, forexample, in the case where channel bit data on an even numbered physicalsector structure shown in FIG. 62A is recorded in an information storagemedium, the data on 2232 channel bits first recorded is included in theleft side small ECC block, and the data on the 2232 channel bitsrecorded next is included in the right side small EC block. Further, thedata on 2232 channel bits recorded next is included in the left sidesmall ECC block. In contrast, in the case where the channel bit data onan odd numbered data structure shown in FIG. 62B is recorded in aninformation storage medium, the data on 2232 channel bits first recordedis included in the right side small ECC block, and the data on the 2232channel bits recorded next is included in the left side small EC block.Further, the data on 2232 channel bits recorded next is included in theright side small ECC block. Thus, the present embodiment is featured inthat the same physical sector is alternately included in two small ECCblocks on a 2232 by 2322 channel bit basis. In other words, a physicalsector is formed in the shape such that the data included in the rightside small ECC block and included in the left side small ECC block arealternately arranged to be distributed on a 2232 by 2332 channel bitbasis, and the formed physical sector is recorded in an informationstorage medium. As a result, there is attained advantageous effect thata structure strong to a burst error can be provided. For example, let usconsider a state in which a lengthwise scratch occurs in acircumferential direction of an information storage medium, and thereoccurs a burst error which disables decoding of data exceeding 172bytes. In this case, a burst error exceeding 172 bytes is arranged to bedistributed in two small ECC blocks. Thus, a burden on error correctionin one ECC block is reduced, and error correction with betterperformance is guaranteed.

The present embodiment is featured by, as shown in FIGS. 62A and 62B, adata structure in a physical sector is different from another dependingon whether or not the physical sector number of a physical sectorconfiguring one ECC block is an even number or an odd number. Namely,

1) Small ECC blocks (right side or left side) to which the first 2232channel bit data of a physical sector belongs are different from eachother; and

2) There is provided a structure in which data on a PO group alternatelydifferent from each other depending on sectors is inserted.

As a result, in order to guarantee a structure in which data ID isarranged at the start position of all the physical sectors even after anECC block has been configured, a data position check at the time ofaccess can be made at a high speed. In addition, POs which belong todifferent small ECC blocks are mixed and inserted into the same physicalsector, structurally simplifying a method employing a PO insertingmethod as shown in FIG. 61, facilitating information sampling on asector by sector manner after error correction processing in aninformation reproducing apparatus; and simplifying an ECC block dataassembling process in an information recording/reproducing apparatus.

In a method for specifically achieving the above contents, POinterleaving and inserting positions have different structures dependingon the left and right. Portions indicated by the narrow double lines(shown in FIG. 61 or portions indicated by the narrow double line andshading indicate the PO interleaving and inserting positions. PO isinserted at the left end in an even numbered physical sector number orat the right end in an odd numbered physical sector number. By employingthis structure, even after an ECC block has configured, data ID isarranged at the start position of a physical sector, thus making itpossible to check a data position at the time of access at high speed.

FIG. 63 shows an embodiment of specific pattern contents from sync codes“SY0” to “SY3” shown in FIGS. 62A and 62B. Three states from State 0 toState 2 are provided in accordance with a modulation rule according tothe present embodiment (a detailed description will be given later).Four sync codes from SY0 to SY3 are set, and each code is selected fromthe left and right groups shown in FIG. 63 according to each state. In acurrent DVD specification, as a modulation system, there employed RLL(2,10) of 8/16 modulation (8 bits are converted to 16 channel bits (aminimum value is 2 and a maximum value is 10 when Run Length Limit: d=2,k=10: “0” continuously lasts), four states from State 1 to State 4,i.e., eight types of sync codes from SY0 to SY7 are set. In comparison,in the present embodiment, types of sync codes are decreased. In aninformation recording/reproducing apparatus or an informationreproducing apparatus, at the time of information reproduction from aninformation storage medium, types of sync code is identified inaccordance with a pattern matching technique. As in the presentembodiment, by significantly decreasing types of sync codes, targetpatterns required for matching are decreased in number; a processingoperation required for pattern matching is simplified; and theprocessing efficiency is improved, making it possible to improve arecognition speed.

In FIG. 63, a bit (channel bit) indicated by “#” denotes a DSV (DigitalSum Value) control bit. As described later, the above DSV control bit isdetermined so as to suppress a DC component by means of a DSV controller(so as to make a value of DSM close to 0). The present embodiment isalso featured in that a polarity inversion channel bit “#” is includedin a sync code. There is attained advantageous effect that a value of“#” can be selected as “1” or “0” so that the DSV value is close to “0”in a macroscopic point of view, including both frame data fields (1092channel bit fields shown in FIGS. 62A and 62B) sandwiching the abovesync code, enabling DSV control from the macroscopic point of view.

As shown in FIG. 63, the sync codes in the present embodiment iscomposed of the sections below.

1) Sync position detecting code section

This section has a common pattern in all sync codes, and forms a fixedcode area. A sync code allocation position can be detected by detectingthis code. Specifically, this section denotes the last 18 channel bits“010000 000000 001001” in each sync code in FIG. 63.

2) Modulation conversion table selector code section

This section forms part of a variable code area, and changes in responseto state number at the time of modulation. The first channel bit shownin FIG. 63 corresponds to this section. That is, in the case where oneof State 1 and State 2 is selected, the first channel bit is set to “1”in any of the codes from SY0 to SYY3. When State 0 is selected, thefirst channel bit of a sync code is set to “1”. However, as anexception, the first channel bit of SY3 in State 0 is set to “0”.

3) Sync frame position identification code section

Part of a variable code area is composed of codes identifying types fromSY0 to SY3 in sync codes. The first to sixth channel bit section in eachsync code shown in FIG. 63 corresponds to this section. As describedlater, a relative position in the same sector can be detected from aconnection pattern of three by three sync codes continuously detected.

4) DC suppressing polarity inversion code section

A channel bit at a position “#” shown in FIG. 63 corresponds to thissection. As described above, this bit is inverted or non-inverted,thereby making close to “0” the DSV value of a channel bit patternincluding the preceding and succeeding frame data.

In the present embodiment, 8/12 modulation (ETM: Eight to TwelveModulation), RLL (1, 10) is employed as a modulation method. That is,eight bits are converted to 12-cahnnel bits at the time of modulation,and a minimum value (d value) is set to 1, and a maximum value (k value)is set to 10 in a range such that the settings “0” after converted arecontinuous. In the present embodiment, although high density can beachieved more significantly than conventionally by setting d=1, it isdifficult to obtain a sufficiently large reproduction signal amplitudeat a site indicated by the mark indicating the highest density.

Therefore, as shown in FIG. 11, an information recording/reproducingapparatus according to the present embodiment has the PR equalizingcircuit 130 and the Viterbi decoder 156, and enables very stable signalreproduction by using a PRML (Partial Response Maximum Likelihood)technique. In addition, k=10 is set, and thus, there is no case in whicheleven or more “0” settings are continuous in the modulated generalchannel bit data. By utilizing this modulation rule, the above syncposition detecting code section has a pattern which hardly appears inthe modulated general channel bit data. That is, as shown in FIG. 63, inthe sync position detecting code section, 12 (=k+2) “0”s arecontinuously arranged. The information recording/reproducing apparatusor the information reproducing apparatus finds this section and detectsa position of the sync position detecting code section. In addition, if“0” continuously lasts too much, a bit shift error is likely to occur.Thus, in order to reduce this problem, in the sync position detectingcode section, a pattern having less continuous “0”s is arrangedimmediately after that portion. In the present embodiment, d=1, andthus, it is possible to set “101” as the corresponding pattern. However,as described above, a sufficiently large reproduction signal amplitudeis hardly obtained at a site of “101” (at a site indicating the highestdensity), and thus, “1001” is arranged instead, obtaining a pattern ofthe sync position detecting code section as shown in FIG. 63.

The present embodiment is featured in that, as shown in FIG. 63, 18channel bits at the back side in a sync code are independently used as(1) sync position detecting code section, and the front side 6 channelbits are used as (2) modulation conversion table selector code section;(3) sync frame position identification code section; or (4) DCsuppression polarity inversion code section. There is attainedadvantageous effect that in the sync codes, the sync position detectingcode section in item (1) is provided independently, thereby facilitatingsingle detection and enhancing sync position detecting precision; thecode sections in items (2) to (4) are used in common in the 6-channelbits, thereby reducing the data size of the whole sync codes (channelbit size); and a sync data occupying rate is increased, therebyimproving substantial data efficiency.

The present embodiment is featured in that, from among four types ofsync codes shown in FIG. 63, only SY0 is arranged at the first syncframe position in a sector, as shown in FIGS. 62A and 62B. Advantageouseffect thereof includes that the start position in a sector can beidentified immediately merely by detecting SY0, and the start positionsampling process in the sector is extremely simplified.

The present embodiment is also featured in that all of the combinationpatterns of three continuous sync codes are different from each other inthe same sector.

A detailed description will be given with respect to the patterncontents of a reference code recorded in the reference code recordingzone RCZ shown in FIGS. 35A to 35C. In a current DVD, an “8/16modulation” system for converting 8-bit data to 16-channel bits isemployed as a modulation system. As a pattern of a reference codeserving as a channel bit pattern recorded in an information storagemedium after modulated, there is employed a repetition pattern“00100000100000010010000010000001”. In comparison with this pattern, inthe present embodiment, ETM modulation for modulating 8-bit data into12-channel bits is used as shown in FIGS. 32 to 34, providing an RLL (1,10) run length restriction. In addition, the PRML technique is employedfor signal reproduction from the data lead-in area DTLDI, data area DTA,data lead-out area DTLDO, and middle area MDA. Therefore, there is aneed for setting the above described modulation rule and a pattern of areference code optimal for PRML detection. In accordance with theRLL(1,10) run length restriction, a minimum value of continuous “0”settings is “d=1”, and is a repetition pattern of “10101010”. Assumingthat a distance from a code “0” to the next adjacent code is “T”, adistance relevant to the adjacent “1” in the above pattern is obtainedas “2 T”. In the present embodiment, in order to achieve high density ofan information storage medium, as described previously, a reproductionsignal from the repetition pattern (“10101010”) of “2 T” recorded on theinformation storage medium is close to a shutdown frequency of MTF(Modulation Transfer Function) characteristics of an objective lens inan optical head (exists in the information recording/reproducing unit141 shown in FIG. 11); and thus, a degree of modulation (signalamplitude) is hardly obtained. Therefore, in the case where areproduction signal from a repetition pattern (“10101010”) of “2 T” hasbeen used as a reproduction signal used for circuit tuning of theinformation reproducing apparatus or the informationrecording/reproducing apparatus (for example, initialing and optimizingtap coefficients in the tap controller 332 shown in FIG. 15), noiseeffect is significant, and stabilization is poor. Therefore, withrespect to a signal after modulated in accordance with RLL(1, 10) runlength restriction, then, it is desirable to carry out circuit tuning byusing a pattern of “3 T” having high density. In the case where adigital sum value (DSV) of the reproduction signal is considered, anabsolute value of a DC (direct current) value increases in proportion tothe number of continuous “0”s between “1” and next “1” that immediatelyfollows it, and the increased value is added to the immediatelypreceding DSV value. The polarity of this added DC value is invertedevery time “1” is reached. Therefore, as a method for setting the DSVvalue to “0” where a channel bit pattern having continuous referencecode is followed, the DSV value is set to be “0” in 12 channel bitpatterns after ETM-modulated, whereby the degree of freedom in referencecode pattern design is increased more significantly by setting to an oddnumber the number of generated “1” appearing in 12 channel bit patternsafter ETM-modulated; offsetting a DC component generated in one set ofreference code cells consisting of a next set. Therefore, in the presentembodiment, the number of “1” appearing in the reference code cellsconsisting of 12 channel bit patterns after ETM-modulated is set to anodd number. In the present embodiment, in order to achieve high density,there is employed a mark edge recording technique in which a location of“1” coincides with a boundary position of a recording mark or an embosspit. For example, in the case where a repetition pattern of “3 T”(“100100100100100100100”) is followed, there occurs a case in which alength of a recording mark or an emboss pit and a length of a spacebetween the mark and pit are slightly different from each otherdepending on a recording condition or an original master producingcondition. In the case where the PRML detecting technique has beenemployed, a level value of a reproduction signal becomes very important.As described previously, even in the case where the length of therecording mark or emboss pit and the length of the space between themark and pit are different from each other, there occurs a necessity ofcorrecting such slightly different component in a circuit manner so asto enable signal detection stably and precisely. Therefore, a referencecode for tuning a circuit constant has a space with a length of “3 T”,like a recording mark or an emboss pit with a length of “3 T”, therebyimproving the precision of tuning a circuit constant. Thus, if a patternof “1001001” is included as a reference code pattern according to thepresent embodiment, the recording mark or emboss pit having the length“3 T”; and a space are always arranged. In addition, circuit tuning alsorequires a pattern in a non-dense state as well as a pattern (“1001001”)having a high density. Therefore, in consideration of that fact that anon-dense state (pattern in which “0” is continuously and frequentlygenerated) is generated at a portion at which a pattern of “1001001” hasbeen excluded from among 12 channel bit patterns after ETM-modulated andthe number of generated “1”s is set in an odd number, with respect to areference code pattern, a repetition of “100100100000” is obtained as anoptical condition, as shown in FIG. 72. In order to ensure that thechannel bit pattern after modulated is produced as the pattern, althoughnot shown, there is a need for setting to “A4h” a data word beforemodulated, when utilizing a modulation table specified in an H format.This data on “A4h” (hexadecimal notation) corresponds to a data symbol“164” (decimal notation).

A description will be given below with respect to how to producespecific data in accordance with the above data conversion rule. First,data symbol “164” (=“0A4h”) is set to main data “D0 to D2047” in thedata frame structure described previously. Next, a data frame 1 to adata frame 15 are pre-scrambled in advance by an initial preset number“0Eh”, and a data frame 16 to a data frame 31 are pre-scrambled inadvance by an initial preset number “0Fh”. If pre-scrambling is appliedin advance, when scrambling is applied in the data conversion ruledescribed previously, scrambling is applied in duplicate, and a datasymbol “164” (=“0A4h”) appears as it is (when scrambling is applied induplicate, an original pattern is returned). When pre-scrambling isapplied to all of the reference codes, each of which is formed of 32physical sectors, DSV control cannot be made, and thus, pre-scramblingcannot be applied to only data frame 0 in advance. After the foregoingscrambling has been applied, if modulation is carried out, a patternshown in FIG. 72 is recorded on the information storage medium.

Referring to FIG. 73, a description will be given with respect to acomparison in data recording format between a variety of informationstorage mediums in the present embodiment. FIG. 73 (a) shows a datarecording format in a conventional read-only type information storagemedium DVD-ROM; a conventional write-once type information storagemedium DVD-R; and a conventional DVD-RW; FIG. 73 (b) shows a datarecording format in a read-only type information storage medium in thepresent embodiment; FIG. 73 (c) shows a data recording format of awrite-once type information storage medium in the present embodiment;and FIG. 73 (d) shows a data recording format of a rewritable-typeinformation storage medium. For the sake of comparison, ECC blocks 411to 418 are shown as the same size. However, one ECC block is composed of16 physical sectors in the conventional read-only type informationstorage medium DVD-ROM shown in FIG. 73 (a); the conventional write-oncetype information storage medium DVD-R; and the conventional rewritabletype information storage medium DVD-RW, whereas, in the presentembodiment shown in FIGS. 73 (b) to 73 (d), one ECC block is composed of32 physical sectors. The present embodiment is featured in that guardareas 442 to 448 having the same length as a sync frame length 433 isprovided between ECC blocks #1 411 to #8 418, as shown in FIGS. 73 (b)to 73 (d). In the conventional read-only type information storage mediumDVD-ROM, ECC blocks #1 411 to #8 418 are continuously recorded as shownin FIG. 73 (a). If an attempt is made to allocate compatibility in datarecording format with the conventional read-only type informationstorage medium DVD-ROM by means of the conventional write-once typeinformation storage medium DVD-R or the conventional rewritable typeinformation storage medium DVD-RW, if an additional writing or rewritingprocess called restricted overwrite is carried out, there has been aproblem that part of the ECC block is damaged due to overwriting and thedata reliability at the time of reproduction is significantly degraded.In contrast, as in the present embodiment, if guard areas 442 to 448 arearranged between data fields (ECC blocks), there is attainedadvantageous effect that an overwrite location is restricted to theguard areas 442 to 448, and the data damage in a data field (ECC block)can be prevented. The present embodiment is secondarily featured in thatthe lengths of the above guard areas 442 to 448 are adjusted to conformwith a sync frame length 433 which is one sync frame size, as shown inFIGS. 73 (a) to 73 (d). As shown in FIGS. 62A and 62B, sync codes arearranged in space in determined sync frame lengths 433 having 1116channel bits, and a sync code position is sampled by utilizing thispredetermined cyclic space in the sync code position detector unit 145shown in FIG. 11. In the present embodiment, there is attainedadvantageous effect that, even if the guard areas 442 to 448 areencompassed at the time of reproduction by making adjustment to conformwith the length sync frame length 433 of the guard areas 442 to 448, thesync frame space is kept unchanged, thus facilitating sync code positiondetection at the time of reproduction.

Further, in the present embodiment, sync data is arranged in the guardarea for the purpose of:

1) improving detection precision of the sync code position detectionwhile matching a generation frequency of the sync codes even in alocation encompassing the guard areas 442 to 448; and

2) facilitating judgment of a position in a physical sector includingthe guard areas 442 to 448.

Specifically, as shown in FIG. 75, a postamble field 481 is formed atthe start position of each of the guard areas 442 to 468, and a synccode “SY1” of sync code number “1” shown in FIG. 63 is arranged in thatpostamble area 481. As is evident from FIGS. 62A and 62B, combinationsof sync code numbers of three continuous sync codes in a physical sectorare different from each other in all locations. Further, combinations ofsync code numbers of three continuous sync codes considering up to synccode numbers “1” in the guard areas 442 to 448 are also different fromeach other in all locations. Therefore, the judgment of a position inphysical sectors including a location of the guard area as well aspositional information in the physical sectors can be made in accordancewith sync code number combinations of three continuous sync codes in anarbitrary area.

FIG. 75 shows a detailed structure in the guard areas 441 to 448 shownin FIG. 73. The present embodiment is featured in that, although astructure in physical sectors is composed of a combination of the synccode 431 and sync data 432, the guard areas 441 to 448 is composed of acombination of a sync code 433 and sync data 434 similarly; and, in anarea of the sync data 434 contained in the guard area #3 443, data isarranged, the data being modulated in accordance with the samemodulation rule as the sync data 432 in sectors. An area in one ECCblock #2 412 composed of 32 physical sectors shown in FIG. 59 isreferred to as a data field 470 in the invention.

VFO (Variable Frequency Oscillator) areas 471 and 472 in FIG. 75 areutilized for synchronization of a reference clock of an informationreproducing apparatus or an information recording/reproducing apparatuswhen the data field 470 is reproduced. As the contents of data recordedin the areas 471 and 472, the data before modulated, in a commonmodulation rule described later, is obtained as a continuous repetitionof “7Eh”, and a channel bit pattern actually described after modulatedis obtained as a repetition of “010001 000100” (pattern in which three“0” settings are repeated). In order to obtain this pattern, it isnecessary to set the start bytes of the VFO areas 471 and 472 to State2.

The pre-sync areas 477 and 478 indicates a boundary position between theVFO areas 471 and 472 and the data area 470, and a recording channel bitpattern after modulated is a repetition of “100000 100000” (pattern inwhich continuous five “0” settings are repeated). The informationreproducing apparatus or the information recording reproducing apparatusdetects a pattern change position of a repetition pattern of “100000100000” in pre-sync areas 477 and 478 and recognizes that the data area470 approaches, from a repetition pattern of “010001 000100” containedin the VFO areas 471 and 472.

A postamble area 481 indicates an end position of the data area 470 anddesignates a start position of the guard area 443. A pattern in thepostamble area 481 coincides with a pattern of “SY1” in a SYNC codeshown in FIG. 63, as described above.

An extra area 482 is an area used for copy control or illegal copyprotection. In particular, in the case where this area is not used forcopy control or illegal copy protection, all “0s” are set by channelbits.

In a buffer area, data before modulated, which is identical to that inthe VFO areas 471 and 472, is obtained as a continuous repetition of“7Eh”, and the actually recorded channel bit pattern after modulated isobtained as a repetition pattern of “010001 000100” (pattern in whichcontinuous three 0 settings are repeated). In order to obtain thispattern, it is necessary to set the start bytes of the VFO areas 471 and472 to State 2.

As shown in FIG. 75, a postamble area 481 in which a pattern of “SY1” isrecorded corresponds to the sync code area 433; and an area from theimmediately succeeding extra area 482 to a pre-sync area 478 correspondsto the sync data area 434. An area from the VFO area 471 to the bufferarea 475 (namely, area including the data area 470 and part of thepreceding and succeeding guard areas) is referred to as a data segment490 in the invention. This area indicates the conditions different fromthose of a “physical segment” described later. The data size of eachitem of data shown in FIG. 75 is expressed by byte number of data beforemodulated.

In the present embodiment, without being limited to a structure shown inFIG. 75, the following method can be employed as another embodiment.That is, the pre-sync area 477 is arranged midway of the VOF areas 471and 472 shown in FIG. 75 instead of allocating the pre-sync area 477 atthe boundary section between the VOF area 471 and the data area 470. Insuch another embodiment, a distance correlation is taken by spacing adistance between a sync code “SY0” and the pre-sync area 477 arranged atthe start position of the data block 470; the pre-sync area 477 is setas pseudo-Sync; and the pre-sync area 477 is set as distance correlationinformation on a real Sync position (although it is different from adistance relevant to another Sync position). If a real Sync positioncannot be detected, Sync is inserted into a position at which the realposition generated from a pseudo Sync position would be detected.Another embodiment is featured in that the pre-sync area 477 is thusspaced slightly from real Sync (“SY0”). When the pre-sync area 477 isarranged at the beginning of the VFO areas 471 and 472, the role of thepre-sync becomes weaken because PLL of a read clock is not locked.

Therefore, it is desirable that the pre-sync area 477 be arranged at theintermediate position of the VFO areas 471 and 472.

In the invention, address information in a recording type(rewritable-type or write-once) information storage medium is recordedin advance by using wobble modulation. The present embodiment isfeatured in that phase modulation of ±90 degrees (180 degrees) is usedas a wobble modulation system, and NRZ (Non Return to Zero) method isemployed, recording address information in advance with respect to aninformation storage medium. A specific description will be given withreference to FIG. 76. In the present embodiment, with respect to addressinformation, the 1-address bit (referred to as an address symbol) area511 is expressed by a four-wobble cycle, and a frequency and anamplitude/a phase are matched everywhere in the 1-address bit area 511.In the case where the same values of address bits are continued, thesame phase continuously lasts at the boundary section of the 1-addressbit areas 511 (at a portion indicated by “triangular mark” shown in FIG.76). In the case where an address bit is inverted, wobble patterninversion (180-degree shift of phase) occurs. In the wobble signaldetector unit 135 of the information recording/reproducing apparatusshown in FIG. 11, a boundary position of the above address bit area 511(location indicated by “triangular mark” shown in FIG. 76) and a slotposition 412 which is a boundary position of a 1-wobble cycle aredetected at the same time. Although not shown in the wobble signaldetector unit 135, a PLL (Phase Lock Loop) circuit is incorporated, andPLL is applied in synchronism with both of the boundary position of theabove address bit area 511 and the slot position 412. If the boundaryposition of this address bit area 511 or the slot position 412 isshifted, the wobble signal detector unit 135 is out of synchronization,disabling precise wobble signal reproduction (reading). A gap betweenthe adjacent slot positions 412 is referred to as a slot gap 513. Asthis slot gap 513 is physically closer, synchronization with a PLLcircuit can be easily obtained, enabling stable wobble signalreproduction (reading of contained information). As is evident from FIG.76, this slot gap 513 coincides with a 1-wobble cycle. As a wobblemodulating method, although an AM (Amplitude Modulation) system forchanging a wobble amplitude is easily affected by dust or scratchadhering to the information storage medium surface, the above phasemodulation is hardly comparatively affected by dust or scratch adheringto the information storage medium surface because a change of a phase isdetected instead of a signal amplitude in the above phase modulation. Asanother modulation system, in an FSK (Frequency Shift Keying) system forchanging a frequency, a slot gap 513 is long with respect to a wobblecycle, and synchronization of a PLL circuit is relatively hardlyobtained. Therefore, as in the present embodiment, when addressinformation is recorded by wobble phase modulation, there is attainedadvantageous effect that a slot gap is narrow, and wobble signalsynchronization is easily obtained.

As shown in FIG. 76, although binary data “1” or “0” is assigned to the1-address bit area 511, a method for allocating bits in the presentembodiment is shown in FIG. 77. As shown on the left side of FIG. 77, awobble pattern, which first wobbles from the start position of onewobble to the outer periphery side, is referred to as an NPW (NormalPhase Wobble), and data “0” is arranged. As shown at the right side, awobble pattern which first wobbles from the start position of one wobbleto the inner periphery side is referred to as an IPW (Invert PhaseWobble), and data “1” is arranged.

A description will be given with respect to an address informationrecording format using wobble modulation in an H format of a write-oncetype information storage medium according to the invention. An addressinformation setting method using wobble modulation in the presentembodiment is featured in that “allocation is carried out in units ofthe sync frame length 433” shown in FIG. 73. As shown in FIGS. 62A and62B, one sector is composed of 26 sync frames, and, as is evident fromFIG. 56, one ECC block is formed of 32 physical sectors. Thus, one ECCblock is composed of 32 physical sectors and is composed of 832(=26×327) sync frames. As shown in FIG. 73, a length of the guard areas442 to 468 which exist between the ECC blocks 411 to 418 coincides withone sync frame length 433, and thus, a length obtained by adding oneguard area 462 and one ECC block 411 to each other is composed of832+1=833 sync frames. Prime factorization can be carried out into833=7×17×7, and thus, a structural allocation utilizing this feature isprovided. That is, a basic unit of data capable of writing an area equalto a length of an area obtained by adding one guard area and one ECCblock to each other is defined as a data segment 531 (A structure in thedata segment 490 shown in FIG. 75 coincides with one another regardlessof the read-only type information storage medium, the rewritable-typeinformation storage medium, or the write-once type information storagemedium); an area having the same length as a physical length of one datasegment 490 is divided into “seven” physical segments, and addressinformation is recorded in advance in the form of wobble modulation on aphysical segment by segment basis. A boundary position relevant to thedata segment 490 and a boundary position relevant to a physical segmentdo not coincide with each other, and are shifted by an amount describedlater. Further, wobble data is divided into 17 WDU (Wobble Data Units),respectively, on a physical segment by segment basis. From the aboveformula, it is evident that seven sync frames are arranged to a lengthof one wobble data unit, respectively. Thus, a physical segment iscomposed of 17 wobble data units, and seven physical segment lengths areadjusted to conform with a data segment length, thereby making it easyto allocate a sync frame boundary and detect a sync code in a rangeencompassing guard areas 442 to 468.

Each of the wobble data units #0 560 to #11 571 is composed of: amodulation area 598 for 16 wobbles; and non-modulation areas 592 and 593for 68 wobbles, as shown in FIGS. 78A to 78D. The present embodiment isfeatured in that an occupying ratio of the non-modulation areas 592 and593 with respect to a modulation area is significantly large. In thenon-modulation areas 592 and 593, a group area or a land area alwayswobbles at a predetermined frequency, and thus, a PLL (Phase LockedLoop) is applied by utilizing the non-modulation areas 592 and 593,making it possible to stably sample (generate) a reference clock whenreproducing a recording mark recorded in the information storage mediumor a recording reference clock used at the time of new recording. Thus,in the present embodiment, an occupying ratio of the non-modulationareas 592 and 593 with respect to a modulation area 598 is significantlyincreased, thereby making it possible to remarkably improve theprecision of sampling (generating) a recording reference clock andremarkably improving the stability of the sampling (generation). Thatis, in the case where phase modulation in wobbles has been carried out,if a reproduction signal is passed through a band path filter for thepurpose of waveform shaping, there appears a phenomenon that a detectionsignal waveform amplitude after shaped is reduced before and after aphase change position. Therefore, there is a problem that, when thefrequency of a phase change point due to phase modulation increases, awaveform amplitude change increases, and the above clock samplingprecision drops; and, conversely, if the frequency of a phase changepoint in a modulation area is low, a bit shift at the time of wobbleaddress information detection is likely to occur. Thus, in the presentembodiment, there is attained advantageous effect that a modulation areaand a non-modulation area due to phase modulation configured, and anoccupying ratio of the non-modulation area is increased, therebyimproving the above clock sampling precision. In the present embodiment,a position of switching the modulation area and the non-modulation areacan be predicted in advance. Thus, a reproduction signal is gated toobtain a signal from the non-modulation area, making it possible tocarry out the above clock sampling from that detection signal. Inaddition, in the case where the recording layer 3-2 is composed of anorganic dye recording material using a principle of recording accordingto the present embodiment, a wobble signal is comparatively hardly takenin the case of using the pre-groove shape/dimensions described in“3-2-D] Basic characteristics relevant to pre-groove shape/dimensions inthe present embodiment” in “3-2) Description of basic characteristicscommon to organic dye film in the present embodiment”. In considerationof this situation, the reliability of wobble signal detection isimproved by significantly increasing an occupying ratio of thenon-modulation areas 590 and 591 with respect to a modulation area, asdescribed above. At the boundary between the non-modulation areas 592and 593 and the modulation area 598, an IPW area is set as a modulationstart mark of the modulation area 598 by using four wobbles or sixwobbles. At a wobble data section shown in FIGS. 78C and 78D, allocationis carried out so that wobble address areas (address bits #2 to #0)wobble-modulated immediately after detecting the IPW area which is thismodulation start mark. FIGS. 78A and 78B each show the contents in awobble data unit #0 560 which corresponds to a wobble sync area 580shown in FIG. 79 (c) described later; and FIGS. 78C and 78D each showthe contents in a wobble data unit which corresponds to a wobble datasection from segment information 727 to a CRC code 726 shown in FIG. 79(c). FIGS. 78A and 78C each show a wobble data unit which corresponds toa primary position 701 in a modulation area described later; and FIGS.78B and 78D each show a wobble data unit which corresponds to asecondary position 702 in a modulation area. As shown in FIGS. 78A and78B, in a wobble sync area 580, six wobbles are allocated to the IPWarea, and four wobbles are allocated to an NPW area surrounded by theIPW area. As shown in FIGS. 78C and 78D, four wobbles are allocated to arespective one of the IPW area and all of the address bit areas #2 to #0in the wobble data section.

FIG. 79 shows an embodiment relating to a data structure in wobbleaddress information in a write-once type information storage medium. Forthe sake of comparison, FIG. 79 (a) shows a data structure in wobbleaddress information of a rewritable-type information storage medium.FIGS. 79 (a) and 79 (c) show two embodiments relating to a datastructure in wobble address information in the write-once typeinformation storage medium.

In a wobble address area 610, three address bits are set by 12 wobbles(referring to FIG. 76). Namely, one address bit is composed of fourcontinuous wobbles. Thus, the present embodiment employs a structure inwhich address information is arranged to be distributed on three bythree address bit basis. When the wobble address information 610 isintensively recorded at one site in an information storage medium, itbecomes difficult to detect all information when dust or scratch adheresto the medium surface. As in the present embodiment, there is attainedadvantageous effect that: wobble address information 610 is arranged tobe distributed on a three by three address bit (12 wobbles) basisincluded in one of the wobble data units 560 to 576; and a set ofinformation is recorded on an integer multiple by multiple address bitbasis of three address bits, enabling information detection of anotheritem of information even in the case where it is difficult to detectinformation in one site due to dust or scratch.

As described above, the wobble address information 610 is arranged to bedistributed, and the wobble address information 610 is completelyarranged on a one by one physical segment basis, thereby making itpossible to identify address information on a physical segment bysegment basis, and thus, identify a current position in physical segmentunits every time an information recording/reproducing apparatus providesan access.

In the present embodiment, an NRZ technique is employed as shown in FIG.76, and thus, a phase does not change in four continuous wobbles in thewobble address area 610. A wobble sync area 580 is set by utilizing thischaracteristic. That is, a wobble pattern which is hardly generated inthe wobble address information 610 is set with respect to the wobblesync area 580, thereby facilitating allocation position identificationof the wobble sync area 580. The present embodiment is featured in that,with respect to wobble address areas 586 and 587 in which one addressbit is composed of four continuous wobbles, one address bit length isset at a length other than four wobbles at a position of the wobble syncarea 580. That is, in the wobble sync area 580, as shown in FIGS. 78Aand 78B, an area (IPW area) in which a wobble bit is set to “1” is setas a wobble pattern change which does not occur in the wobble datasection as shown in FIGS. 78C and 78D such as “six wobble→fourwobbles→six wobbles”. When a method for changing a wobble cycle asdescribed above is utilized as a specific method for setting a wobblepattern which can be hardly generated in the wobble data section withrespect to the wobble sync area 580, the following advantageous effectscan be attained:

1) Wobble detection (wobble signal judgment) can be stably continuedwithout distorting PLL relating to the slot position 512 (FIG. 76) of awobble which is carried out in the wobble signal detector unit 135 shownin FIG. 11; and

2) A wobble sync area 580 and modulation start marks 561 and 562 can beeasily detected due to a shift of an address bit boundary positiongenerated in the wobble signal detector unit 135 shown in FIG. 11.

As shown in FIGS. 78A to 78D, the present embodiment is featured in thatthe wobble sync area 580 (is formed in 12 wobble cycles, and a length ofthe wobble sync area 580 is made coincident with three address bitlengths. In this manner, all the modulation areas (for 16 wobbles) inone wobble data unit #0 560 are arranged to the wobble sync area 580,thereby improving detection easiness of the start position of wobbleaddress information 610 (allocation position of wobble sync area 580).This wobble sync area 580 is arranged in the first wobble data unit in aphysical segment. Thus, there is attained advantageous effect that thewobble sync area 580 is arranged to the start position in a physicalsegment, whereby a boundary position of the physical segment can beeasily sampled merely by detecting a position of the wobble sync area580.

As shown in FIGS. 78C and 78D, in wobble data units #1 561 to #11 571,the IPW area (refer to FIG. 77) is arranged as a modulation start markat the start position, the area preceding address bits #2 to #0. Thewaveform of NPW is continuously formed in the non-modulation areas 592and 593 arranged at the preceding position. Thus, the wobble signaldetector unit 135 shown in FIG. 11 detects a turning point from NPW toIPW is detected, and samples the position of the modulation start mark.

As a reference, the contents of wobble address information 610 containedin a rewritable-type information storage medium shown in FIG. 79 (a) areas follows:

1) Physical Segment Address 601

Information indicating a physical segment number in a track (within onecycle in an information storage medium 221);

2) Zone Address 602

This address indicates a zone number in the information storage medium221; and

3) Parity Information 605

This information is set for error detection at the time of reproductionfrom the wobble address information 610; 14 address bits from reservedinformation 604 to the zone address 602 are individually added in unitsof address bits; and a display as to whether or not a result of theaddition is an even number or an odd number is made. A value of theparity information 605 is set so that a result obtained by takingexclusive OR in units of address bits becomes “1” with respect to atotal of 15 address bits including one address bit of this addressparity information 605.

4) Unity Area 608

As described previously, each wobble data unit is set so as to becomposed of a modulation area 598 for 16 wobbles and non-modulationareas 592 and 593 for 68 wobbles, and an occupying ratio of thenon-modulation areas 592 and 593 with respect to the modulation area 598is significantly increased. Further, the precision and stability ofsampling (generation) of a reproducing reference clock or a recordingreference clock is improved more remarkably by increasing the occupyingratio of the non-modulation areas 592 and 593. The NPW area is fullycontinuous in a unity area 608, and is obtained as a non-modulation areahaving its uniform phase.

FIG. 79 (a) shows the number of address bits arranged to each item ofthe above described information. As described above, the wobble addressinformation 610 is divided on a three by three address bits, and thedivided items of the information are arranged to be distributed in eachwobble data unit. Even if a burst error occurs due to the dust orscratch adhering to a surface of an information storage medium, there isa very low probability that such an error propagates across the wobbledata units which are different from each other. Therefore, a contrivanceis made so as to reduce to the minimum the count encompassing thedifferent wobble data units as locations in which the same informationis recorded and to match the turning point of each items of informationwith a boundary position of a wobble data unit. In this manner, even ifa burst error occurs due to the dust or scratch adhering to a surface ofan information storage medium, and then, specific information cannot beread, the reliability of reproducing of wobble address information isimproved by enabling reading of another item of information recorded inanother one of the wobble data units.

As shown in FIGS. 79 (a) to 79 (d), the present embodiment is featuredin that the unity areas 608 and 609 are arranged at the end in thewobble address information 610. As described above, in the unity areas608 and 609, a wobble waveform is formed in the shape of NPW, and thus,the NPW continuously lasts in substantially three continuous wobble dataunits. There is attained advantageous effect that the wobble signaldetector unit 135 shown in FIG. 11 makes a search for a location inwhich NPW continuously lasts in a length for three wobble data units 576by utilizing this feature, thereby making it possible to easily sample aposition of the unity area 608 arranged at the end of the wobble addressinformation 610, and to detect the start position of the wobble addressinformation 610 by utilizing the positional information.

From among a variety of address information shown in FIG. 79 (a), aphysical segment address 601 and a zone address 602 indicate the samevalues between the adjacent tracks, whereas a value changes between theadjacent tracks in a groove track address 606 and a land track address607. Therefore, an indefinite bit area 504 appears in an area in whichthe groove track address 606 and the land track address 607 arerecorded. In order to reduce a frequency of this indefinite bit, in thepresent embodiment, an address (number) is displayed by using a graycode with respect to the groove track address 606 and the land trackaddress 607. The gray code denotes a code in the case where a code afterconverted when an original value changes by “1” only changes by “onebit” anywhere. In this manner, the indefinite bit frequency is reduced,making it possible to detect and stabilize a reproduction signal from arecording mark as well as a wobble detecting signal.

As shown in FIGS. 79 (b) and 79 (c), in a write-once type informationstorage medium as well, as in the rewritable-type information storagemedium, a wobble sync area 580 is arranged at the start position of aphysical segment, thereby making it easy to detect the start position ofthe physical segment or a boundary position between the adjacentsegments. Type identification information 721 on the physical segmentshown in FIG. 79B indicates an allocation position in the physicalsegment as in the wobble sync pattern contained in the above describedwobble sync area 580, thereby making it possible to predict in advancean (allocation location of another modulation area 598 in the samephysical segment and to prepare for next modulation area detection.Thus, there is attained advantageous effect that the precision of signaldetection (judgment) in a modulation area can be improved. Specifically,

When type identification information 721 on a physical segment is set to“0”, it denotes that all the items of information in the physicalsegment shown in FIG. 81 (b) are arranged at a primary position or thata primary position and a secondary position shown in FIG. 81 (d) aremixed; and

When type identification information 721 of a physical segment is set to“1”, all items of information in a physical segment are arranged at asecondary position, as shown in FIG. 81 (c).

According to another embodiment relevant to the above describedembodiment, it is possible to indicate an allocation location of amodulation area in a physical segment by using a combination between awobble sync pattern and type identification information 721 on aphysical segment. By using the combination of the two types ofinformation described previously, three or more types of allocationpatterns of modulation areas shown in FIGS. 81 (b) to 81 (d) can beexpressed, making it possible to provide a plurality of allocationpatterns of the modulation areas. While the above described embodimentshows an allocation location of a modulation area in a physical segmentwhich includes a wobble sync area 580 and type identificationinformation 721 on a physical segment, the invention is not limitedthereto. For example, as another embodiment, the wobble sync area 580and the type identification information 721 on the physical segment mayindicate an allocation location of a modulation area in a next physicalsegment. By doing this, in the case where tracking is carried outcontinuously along a groove area, there is attained advantageous effectthat the allocation location of the modulation area in the next physicalsegment can be identified in advance, and a long preparation time fordetecting a modulation area can be taken.

Layer number information 722 in a write-once type information storagemedium shown in FIG. 79 (b) indicates either of the recording layersfrom among a single-sided single-layer or a single-sided double-layer.This information denotes:

“L0 later” in the case of a single-sided single-layer medium or asingle-sided double-layer medium when “0” is set (a front layer at thelaser light beam incident side); and

“L1 layer” of a single-sided double-layer when “1” is set (a rear layerin viewed from the laser light beam incident side).

Physical segment sequence information 724 indicates an allocationsequence of relative physical segments in the same physical segmentblock. As is evident as compared with FIG. 79 (a), the start position ofthe physical segment sequence information 724 contained in wobbleaddress information 610 coincides with that of a physical segmentaddress 601 contained in a rewritable-type information storage medium.The physical segment sequence information position is adjusted toconform with the rewritable-type medium, thereby making it possible toimprove compatibility between medium types and to share or simplify anaddress detection control program using a wobble signal in aninformation recording/reproducing apparatus in which both of arewritable-type information storage medium and a write-once typeinformation storage medium can be used.

A data segment address 725 shown in FIG. 79 (b) describes addressinformation on a data segment in numbers. As has already been described,in the present embodiment, one ECC block is composed of 32 sectors.Therefore, the least significant five bits of a physical sector numberof a sector arranged at the beginning in a specific ECC block coincideswith that of a sector arranged at the start position in the adjacent ECCblock. In the case where a physical sector number has beet set so thatthe least significant five bits of the physical sector number of asector arranged in an ECC block are “00000”, the values of the leastsignificant six bits or more of the physical sector numbers of all thesectors which exist in the same ECC block coincide with each other.Therefore, the least significant five bit data of the physical sectornumber of the sectors which exist in the same ECC block is eliminated,and address information obtained by sampling only the least significantsix bits or more is defined as an ECC block address (or ECC blockaddress number). A data segment address 725 (or physical segment blocknumber information) recorded in advance by wobble modulation coincideswith the above ECC block address. Thus, when positional information on aphysical segment block due to wobble modulation is indicated by a datasegment address, there is advantageous effect that a data amountdecreases on five by five bit basis as compared with when the address isdisplayed by a physical sector number, simplifying current positiondetection at the time of an access.

A CRC code 726 shown in FIGS. 79 (b) and 79 (c) is a CRC code (errorcorrection code) arranged to 24 address bits from physical segment typeidentification information 721 to the data segment address 725 or a CRCcode arranged to 24 address bits from segment information 727 to thephysical segment sequence information 724. Even if a wobble modulationsignal is partially mistakenly read, this signal can be partiallycorrected by this CRC code 726.

In a write-once type information storage medium, an area correspondingto 15 address bits is arranged to the unity area 609, and an NPW area isfully arranged in five wobble data units 12 to 16 (the modulation area598 does not exist).

A physical segment block address 728 shown in FIG. 79 (c) is an addressset for each physical segment block which configure one unit from sevenphysical segments, and a physical segment block address relevant to thefirst segment block in the data lead-in area DTRDI is set to “1358h”.The values of the physical segment block addresses are sequentiallyadded one by one from the first physical segment block contained in thedata lead-in area DTLDI to the last physical segment block contained inthe data lead-out area DTLDO, including the data area DTA.

The physical segment sequence information 724 denotes the sequence ofeach of the physical segments in one physical segment block, and “0” isset to the first physical segment, and “6” is set to the last physicalsegment.

The embodiment shown in FIG. 79 (c) is featured in that the physicalsegment block address 728 is arranged at a position which precedes thephysical segment sequence information 724. For example, as in the RMDfield 728 shown in FIG. 53, address information is often managed by thisphysical segment block address. In the case where an access is providedto a predetermined segment block address in accordance with these itemsof management information, first, the wobble signal detector unit 135shown in FIG. 11 detects a location of the wobble sync area 580 shown inFIG. 79 (c), and then, sequentially decodes items of informationrecorded immediately after the wobble sync area 580. In the case where aphysical segment block address exists at a position which precedes thephysical segment sequence information 724, first, the physical segmentblock address is decoded, and it is possible to judge whether or not apredetermined physical segment block address exists without decoding thephysical segment sequence information 724. Thus, there is advantageouseffect that access capability using a wobble address is improved.

The segment information 727 is composed of type identificationinformation 721 and a reserved area 723. The type identificationinformation 721 denotes an allocation location of a modulation area in aphysical segment. In the case where the value of this typeidentification information 721 is set to “0b”, it denotes a state shownin FIG. 81 (b) described layer. In the case where the information is setto “1b”, it denotes a state shown in FIG. 81 (c) or FIG. 81 (d)described later.

The present embodiment is featured in that type informationidentification 721 is arranged immediately after the wobble sync area580 in FIG. 79 (c). As described above, first, the wobble signaldetector unit 135 shown in FIG. 11 detects a location of the wobble syncarea 580 shown in FIG. 79 (c), and then, sequentially decodes the itemsof information recorded immediately after the wobble sync area 580.Therefore, the type identification information 721 is arrangedimmediately after the wobble sync area 580, thereby enabling anallocation location check of a modulation area in a physical segmentimmediately. Thus, high speed access processing using a wobble addresscan be achieved.

In the write-once type information storage medium according to thepresent embodiment, a recording mark is formed on a groove area, and aCLV recording system is employed. In this case, as described previously,a wobble slot position is shifted between the adjacent tracks, and thus,interference between the adjacent wobbles is likely to occur with awobble reproduction signal. In order to eliminate this effect, in thepresent embodiment, a contrivance is made to shift a modulation area sothat modulation areas do not overlap each other between the adjacenttracks.

Specifically, as shown in FIG. 80, a primary position 701 and asecondary position 702 can be set in an allocation location of amodulation area. Basically, assuming that after allocation has beenfully carried out in the primary position, there occurs a location inwhich modulation areas partially overlap between the adjacent tracks,there is employed a method for partially shift the modulation area tothe secondary position. For example, in FIG. 80, when a modulation areaof a groove area 505 is set at the primary position, a modulation areaof the adjacent groove area 502 and a modulation area of a groove area506 partially overlap on each other. Thus, the modulation area of thegroove area 505 is shifted to the secondary position. In this manner,there is attained advantageous effect that a wobble address can bestably reproduced by preventing the interference between the modulationareas of the adjacent tracks in a reproduction signal from a wobbleaddress.

The specific primary position and secondary position relating to amodulation area is set by switching an allocation location in the samewobble data unit. In the present embodiment, an occupying ratio of anon-modulation area is set to be higher than a modulation area so that,the primary position and the secondary position can be switched merelyby making a mere allocation change in the same wobble data unit.Specifically, in the primary position 701, as shown in FIGS. 78 (a) and78 (c), the modulation area 598 is arranged at the start position in onewobble data unit. In the secondary position 702, as shown in FIGS. 78(b) and 78 (d), the modulation area 598 is arranged at the latter halfposition in one of the wobble data unit 560 to 571.

A coverage of the primary position 701 and the secondary position 702shown in FIGS. 78 (a) to 78 (d), i.e., a range in which the primaryposition or the secondary position continuously lasts is defined in therage of physical segments in the present embodiment. That is, as shownin FIGS. 81 (b) to 81 (d), after three types (plural types) ofallocation patterns of modulation areas in the same physical segmenthave been provided, when the wobble signal detector unit 135 shown inFIG. 11 identifies an allocation pattern of a modulation area in aphysical segment from the information contained in the typeidentification information 721 on a physical segment, the allocationlocation of another modulation area 598 in the same physical segment canbe predicted in advance. As a result, there is attained advantageouseffect that preparation for detecting a next modulation area can bemade, thus making it possible to improve the precision of signaldetection (judgment).

FIG. 81 (b) shows allocation of wobble data units in a physical segment,wherein the number described in each frame indicate wobble data unitnumbers in the same physical segment. A 0-th wobble data unit arereferred to as a sync field 711 as indicated at a first stage. A wobblesync area exists in a modulation area in this sync field. First toeleventh wobble data units are referred to as an address field 712.Address information is recorded in a modulation area contained in thisaddress field 712. Further, in twelfth to sixteenth wobble data units,all of the wobble patterns are formed in an NPW unity field 713.

A mark “P” described in FIGS. 81 (b), 81 (c) and 81 (d) indicates that amodulation area is set at a primary position in a wobble data unit; anda mark “S” indicates that a modulation area is set at a secondaryposition in a wobble data unit. A mark “U” indicates that a wobble dataunit is included in a unity field 713, and a modulation area does notexist. An allocation pattern of a modulation area shown in FIG. 81 (b)indicates that all the areas in a physical segment are set at theprimary position; and an allocation pattern of a modulation area shownin FIG. 81 (c) indicates all areas in a physical segment are set at thesecondary position. In FIG. 81 (d), the primary position and thesecondary position are mixed in the same physical segment; a modulationarea is set at the primary position in each of 0-th to fifth wobble dataunits, and a modulation area is set at the secondary position in each ofsixth to eleventh wobble data units. As shown in FIG. 81 (d), theprimary positions and the secondary positions are half divided withrespect to an area obtained by adding a sync field 711 and an addressfield 712, thereby making it possible to finely prevent an overlap ofmodulation areas between the adjacent tracks.

Now, a description will be given with respect to a method for recordingthe data segment data described previously with respect to the physicalsegment or the physical segment block in which address information isrecorded in advance by wobble modulation described above. Data isrecorded in recording cluster units serving as units of continuouslyrecording data in both of a rewritable-type information storage mediumand a write-once type information storage medium. FIGS. 82A and 82B showa layout in this recording cluster. In recording clusters 540 and 542,one or more (integer numbers) of data segments continuously lasts, andan expanded guard field 528 or 529 is set at the beginning or at the endof the segment. The expanded guard fields 528 and 529 are set in therecording clusters 540 and 542 so as to be physically overlapped andpartially overwritten between the adjacent recording clusters so as notto produce a gap between the adjacent recording clusters when data isnewly additionally written or rewritten in units of the recordingclusters 540 and 542. As the position of each of the expanded guardfields 528 and 529 set in the recording clusters 540 and 542, in theembodiment shown in FIG. 82A, the expanded guard field 528 is arrangedat the end of the recording cluster 540. In the case where this methodis used, the expanded guard field 528 follows a post amble area 526shown in FIG. 83 (a). Thus, in particular, in the write-once typeinformation storage medium, the post-amble area 526 is not mistakenlydamaged at the time of rewriting; protection of the post-amble area 526at the time of rewriting can be carried out; and the reliability ofposition detection using the post amble area 526 at the time of datareproduction can be arranged. As another embodiment, as shown in FIG.82B, the expanded guard field 529 can also be arranged at the beginningof the recording cluster 542. In this case, as is evident from acombination of FIG. 82B and FIGS. 83 (a) to 83 (f), the expanded guardfield 529 immediately precedes a VFO area 522. Thus, at the time ofrewriting or additional writing, the VFO area 522 can be sufficientlytaken long, and thus, a PLL lead-in time relating to a reference clockat the time of reproduction of a data field 525 can be taken long,making it possible to improve the reliability of reproduction of datarecorded in the data field 525. In this way, there is attainedadvantageous effect that a structure composed of data segments in thecase where one or more recording clusters denote writing units isprovided, thereby making it possible to facilitate a mixing recordingprocess with respect to the same information storage medium, PC data (PCfiles) of which a small amount of data is often rewritten many times andAV data (AV file) of which a large amount of data is continuouslyrecorded one time. That is, with respect to data used for a personalcomputer, a comparatively small amount of data is often rewritten manytimes. Therefore, a recording method suitable for PC data is obtained byminimally setting data units of rewriting or additional writing. In thepresent embodiment, as shown in FIG. 56, an ECC block is composed of 32physical sectors. This, a minimum unit for efficiently carrying outrewriting or additional writing is obtained by carrying out rewriting oradditional writing in data segment units including only one ECC block.Therefore, a structure in the present embodiment in which one or moredata segments are included in a recording cluster which denotesrewriting units or additional writing units is obtained as a recordingstructure suitable for PC data (PC files). In AV (Audio Video) data, itis necessary to continuously record a very large amount of video imageinformation and voice information smoothly without any problem. In thiscase, continuously recorded data is collectively recorded as onerecording cluster. At the time of AV data recording, when a random shiftamount, a structure in a data segment, or a data segment attribute andthe like is switched on a data segment by segment basis configuring onerecording cluster, a large amount of time is required for such aswitching process, making it difficult to carry out a continuousrecording process. In the present embodiment, as shown in FIGS. 82A and82B, it is possible to provide a recording format suitable for AV datarecording for continuously recording a large amount of data byconfiguring a recording cluster while data segments in the same format(without changing an attribute or a ransom shift amount and withoutinserting specific information between data segments) are continuouslyarranged. In addition, a simplified structure in a recording cluster isachieved, and simplified recording control circuit and reproductiondetector circuit are achieved, making it possible to reduce the price ofan information recording/reproducing apparatus or an informationreproducing apparatus. A data structure in recording cluster 540 inwhich data segments (excluding the expanded guard field 528) in therecording cluster shown in FIGS. 82A and 82B are continuously arrangedis completely identical to those of the read-only information storagemedium shown in FIG. 73 (b) and the write-once type information storagemedium shown in FIG. 73 (c). In this way, a common data structure isprovided among all of the information storage mediums regardless of theread-only type, the write-once type, or the rewritable-type, thusallocating medium compatibility. In addition, a detector circuit of theinformation recording/reproducing apparatus or the informationreproducing apparatus whose compatibility has been arranged can be usedin common; high reliability of reproduction can be arranged; and pricereduction can be achieved.

By employing the structure shown in FIGS. 82A and 82B, random shiftamounts of all the data segments inevitably coincide with each other inthe recording cluster. In the rewritable-type information medium, arecording cluster is recorded by random shifting. In the presentembodiment, the random shift amounts of all the data segments coincidewith each other in the same recording cluster 540. Thus, in the casewhere reproduction has been carried out across the different datasegments from each other in the same recording cluster 540, there is noneed for synchronization adjustment (phase resetting) in a VFO area(reference numeral 522 in FIG. 83 (d)), making it possible to simplify areproduction detector circuit at the time of continuous reproduction andto allocate high reliability of reproduction detection.

FIG. 83 shows a method for recording data to be rewritably recorded in arewritable-type information storage medium. Now, although a descriptionwill be given while focusing on a rewritable-type information storagemedium, it should be noted that an additional writing method relevant toa write-once type information storage medium is basically identical tothe above recording method. A layout in the recording cluster in awrite-once type information storage medium according to the presentembodiment will be described in way of example employing a layout shownin FIG. 82A. The present embodiment is not limited thereto, and a layoutshown in FIG. 82B may be employed for a rewritable-type informationstorage medium. In the present embodiment, rewriting relating torewritable data is carried out in units of the recording clusters 540and 541 shown in FIGS. 82B and 83 (e). As described later, one recordingcluster is composed of one or more data segments 529 to 531 and anexpanded guard field 528 arranged at the end. That is, the startposition of one recording cluster 631 coincides with that of the datasegment 531, and the cluster starts from the VFO area 522. In the casewhere a plurality of data segments 529 and 530 are continuouslyrecorded, the plurality of data segments 529 and 530 are continuouslyarranged in the same recording cluster 531. In addition, the buffer area547 which exists at the end of the data segment 529 and the VFO area 532which exists at the beginning of a next data segment continuously last,and thus, a phase (of a recording reference clock) at the time ofrecording) between these areas coincides with one another. Whencontinuous recording terminates, an expanded guard area 528 is arrangedat the end position of the recording cluster 540. The data size of thisexpanded guard area 528 is equal to the size for 24 data bytes as databefore modulated.

As is evident from a correlation between

FIGS. 83 (a) and 83 (c), rewritable-type guard areas 461 and 462 eachinclude: post amble areas 546 and 536; extra areas 544 and 534; bufferareas 547 and 537; VFO areas 532 and 522; and pre-sync areas 533 and523, and an expanded guard field 528 is arranged only in location inwhich continuous recording terminates. The present embodiment isfeatured in that rewriting or additional writing is carried out so thatthe expanded guard area 528 and the succeeding VFO area 522 partiallyoverlap each other at a duplicate site 591 at the time of rewriting. Byrewriting or additional writing while partial duplication is maintained,it is possible to prevent a gap (area in which no recording mark isformed) from being produced between the recording clusters 540 and 541.In addition, a stable reproduction signal can be detected by eliminatinginter-layer cross talk in an information storage medium capable ofcarrying out recording in a single-sided double recording layer.

The data size which can be rewritten in one data segment in the presentembodiment is 67+4+77376+2+4+16=77469 (data bytes). One wobble data unit560 is 6+4+6+68=84 (wobbles). One physical segment 550 is composed of 17wobble data units, and a length of seven physical segments 550 to 556coincides with that of one data segment 531. Thus, 84×17×7=9996(wobbles) are arranged in the length of one data segment 531. Therefore,from the above formula, 77496/9996=7.75 (data bytes/wobble) correspondsto one wobble.

As shown in FIG. 84, an overlap portion of the succeeding VFO area 522and the expanded guard field 528 follows 24 wobbles from the startposition of a physical segment, and the starting 16 wobbles of aphysical segment 550 are arranged in a wobble sync area 580, and thesubsequent 68 wobbles are arranged in a non-modulation area 590.Therefore, an overlap portion of the VFO area 522 which follows 24wobbles and the expanded guard field 528 is included in thenon-modulation area 590. In this way, the start position of a datasegment follows the 24 wobbles from the start position of a physicalsegment, whereby the overlap portion is included in the non-modulationarea 590. In addition, a detection time and a preparation time forrecording process of the wobble sync area 580 can be sufficiently taken,and thus, a stable and precise recording process can be guaranteed.

A phase change recording film is used as a recording film of therewritable-type information storage medium in the present embodiment. Inthe phase change recording film, degradation of the recording filmstarts in the vicinity of the rewriting start/end position. Thus, ifrecording start/recording end at the same position is repeated, thereoccurs a restriction on the number of rewritings due to the degradationof the recording film. In the present embodiment, in order to alleviatethe above described problem, at the time of rewriting, J_(M+1)/12 databytes are shifted as shown in FIG. 84, and the recording start positionis shifted at random.

Although the start position of the expanded guard field 528 coincideswith that of the VFO area 522 in order to explain a basic concept inFIGS. 83 (c) and 83 (d), strictly, the start position of the VFO area522 is shifted at random, as shown in FIG. 84, in the presentembodiment.

A phase change recording film is used as a recording film in a DVD-RAMdisk which is a current rewritable-type information storage medium aswell, the start/end positions of recording is shifted at random for thepurpose of improving the rewriting count. The maximum shift amount rangewhen random shifting has been carried out in the current DVD-RAM disk isset to 8 data bytes. A channel bit length (as data after modulated, tobe recorded in a disk) in the current DVD-RAM disk is set to 0.143 μm onaverage. In the rewritable-type information storage medium according tothe present embodiment, an average length of channel bits is obtained as(0.087+0.093)/2=0.090 (μm). In the case where a length of a physicalshift range is adjusted to conform with the current DVD-RAM disk, byusing the above value, the required minimal length serving as a randomshift range in the present embodiment is obtained as:8 bytes×(0.143 μm/0.090 μm)=12.7 bytes

In the present embodiment, in order to allocate easiness of areproduction signal detecting process, the unit of random shift amounthas been adjusted to conform with “channel bits” after modulated. In thepresent embodiment, ETM modulation (Eight to Twelve modulation) forconverting 8 bits to 12 bits is used, and thus, formula expression whichindicates a random shift amount is designated by J_(m)/12 (data bytes)while a data byte is defined as a reference. Using the value of theabove formula, a value which can be taken by J_(m) is 12.7×12=152.4, andthus, J_(m) ranges 0 to 152. For the above described reason, in therange meeting the above formula, a length of the random shift rangecoincides with the current DVD-RAM disk, and the rewriting count similarto the current DVD-RAM disk can be guaranteed. In the presentembodiment, a margin is slightly provided with respect to the requiredminimal length in order to allocate the current or more rewriting count,and the length of the random shift range has been set to 14 (databytes). From these formulas, 14×12=168 is established, and thus, a valuewhich can be taken by J_(m) has been set in the range of 0 to 167. Asdescribed above, the random shift amount is defined in a range which iswider than J_(m)/12 (0≦J_(m)≦154), whereby a length of a physical rangerelevant to the random shift amount coincides with that of the currentDVD-RAM. Thus, there is attained advantageous effect that the repetitionrecording count similar to that of the current DVD-RAM can beguaranteed.

In FIG. 83 (c), the lengths of the buffer area 547 and the VFO area 532in the recording cluster 540 become constant. As is evident from FIG. 82(a) as well, the random shift amount J_(m) of all the data segments 529is obtained as the same value everywhere in the same recording cluster540. In the case of continuously recording one recording cluster 540which includes a large amount of data segments, a recording position ismonitored from a wobble. That is, a position of the wobble sync area 580shown in FIGS. 79 (a) to 79 (c) is detected, and, in the non-modulationareas 592 and 593 shown in FIGS. 78 (c) and 78 (d), the check of therecording position on the information storage medium is made at the sametime as recording while the number of wobbles is counted. At this time,a wobble slip (recording at a position shifted by one wobble cycle)occurs due to mistaken wobble count or rotation non-uniformity of arotary motor which rotates the information storage medium, and therecording position on the information storage medium is rarely shifted.The information storage medium according to the present embodiment isfeatured in that, in the case where a recording position shift generatedas described above has been detected, adjustment is made in therewritable-type guard area 461 shown in FIG. 83 (a), and recordingtiming correction is carried out in the guard area 461. Now, an H formatwill be described here. This basic concept is employed in a B format,described later. In FIGS. 83 (a) to 83 (f), although importantinformation for which bit missing or bit duplication cannot be allowedis recorded in a postamble area 546, an extra area 544, and a pre-syncarea 533, a specific pattern is repeated in the buffer area 547 and theVFO area 532. Thus, as long as this repetition boundary position isarranged, missing or duplication of only one pattern is allowed.Therefore, in the present embodiment, in particular, adjustment is madein the buffer area 547 or the VFO area 532, and recording timingcorrection is carried out.

As shown in FIG. 84, in the present embodiment, an actual start pointposition defined as a reference of position setting is set so as tomatch a position of wobble amplitude “0” (wobble center). However, theposition detecting precision of a wobble is low, and thus, in thepresent embodiment, the actual start point position allows a shiftamount up to a maximum of ±1 data byte”, as “±1 max” in FIG. 84 isdescribed.

In FIGS. 83 (a) to 83 (f) and 84, the random shift amount in the datasegment 530 is defined as J_(m) (as described above, the random shiftamounts of all the data segments 529 coincide with each other in therecording cluster 540); and the random shift amount of the data segment531 to be additionally written is defined as J_(m+1). As a value whichcan be taken by J_(m) and J_(m+1) shown in the above formula, forexample, when an intermediate value is taken, J_(m)=J_(m+1)=84 isobtained. In the case where the positional precision of an actual startpoint is sufficiently high, the start position of the expanded guardfield 528 coincides with that of the VFO area 522, as shown in (FIGS. 83(c) and 83 (d).

In contrast, after the data segment 530 is recorded at the maximum backposition, in the case where the data segment 531 to be additionallywritten or rewritten has then been recorded in the maximum frontposition, the start position of the VFO area 522 may enter a maximum 15data bytes in the buffer area 537. Specific important information isrecorded in the extra area 534 that immediately precedes the buffer area537. Therefore, in the present embodiment, a length of the buffer area537 requires 16 data bytes or more. In the embodiment shown in FIG. 83(c), a data size of the buffer area 537 is set to 15 data bytes inconsideration of a margin of one data byte.

As a result of a random shift, if a gap occurs between the expandedguard area 528 and the VFO area 522, in the case where a single-sideddouble recording layer structure has been employed, there occurs aninter-layer crosstalk at the time of reproduction due to that gap. Thus,even if a random shift is carried out, a contrivance is made such thatthe expanded guard field 528 and the VFO area 522 partially overlap eachother, and a gap is not produced. Therefore, in the present embodiment,it is necessary to set the length of the expanded guard field 528 to beequal to or greater than 15 data bytes. The succeeding VFO area 522sufficiently takes 71 data bytes. Thus, even if an overlap area of theexpanded guard field 528 and the VFO area 522 slightly widens, there isno obstacle at the time of signal reproduction (because a time forobtaining synchronization of reproduction reference clocks issufficiently arranged in the VFO area 522 which does not overlap).Therefore, it is possible to set the value of the expanded guard field528 to be greater than 15 data bytes. As has already been described, awobble strip rarely occurs at the time of continuous recording, and arecording position may be shifted by one wobble cycle. One wobble cyclecorresponds to 7.75 (≈8) data bytes, and thus, in the presentembodiment, a length of the expanded guard field 528 is set to equal toor greater than 23 (=15+8) data bytes. In the embodiment shown in FIG.83 (c), like the buffer area 537, the length of the expanded guard field528 is set to 24 data bytes in consideration of a margin of one databyte similarly.

In FIG. 83 (e), it is necessary to precisely set the recording startposition of the recording cluster 541. The informationrecording/reproducing apparatus according to the present embodimentdetects this recording start position by using a wobble signal recordedin advance in the rewritable-type or write-once type information storagemedium. As shown in FIGS. 78A to 78D, in all areas other than the wobblesync area 580, a pattern changes from NPW to IPW in units of fourwobbles. In comparison, in the wobble sync area 580, wobble switchingunits are partially shifted from four wobbles, and thus, the wobble syncarea 580 can detect a position most easily. Thus, the informationrecording/reproducing apparatus according to the present embodimentdetects a position of the wobble sync area 580, and then, carries outpreparation for a recording process, and starts recording. Thus, it isnecessary to arrange a start position of a recording cluster 541 in anon-modulation area 590 immediately after the wobble sync area 580. FIG.84 shows the contents of the allocation. The wobble sync area 580 isarranged immediately after switching position of a physical segment. Thelength of the wobble sync area 580 is defined by 16 wobble cycles.Further, after detecting the wobble sync area 580, eight wobble cyclesare required for preparation for the recording process in considerationof a margin. Therefore, as shown in FIG. 84, even in consideration of aransom shift, it is necessary that the start position of the VFO area522 which exists at the start position of the recording cluster 541 isarranged rearwardly by 24 wobbles or more from a switching position of aphysical segment.

As shown in FIG. 83, a recording process is carried out many times in aduplicate site 591 at the (time of rewriting. When rewriting isrepeated, a physical shape of a wobble groove or a wobble land changes(is degraded), and the wobble reproduction signal amount is lowered. Inthe present embodiment, as shown in FIG. 83 (f), a contrivance is madeso that a duplicate site 591 at the rewriting or at the time ofadditional writing is recorded in the non-modulation area 590 instead ofarriving in the wobble sync area 580 or wobble address area 586. In thenon-modulation area 590, a predetermined wobble pattern (NPW) is merelyrepeated. Thus, even if a wobble reproduction signal amount is partiallydegraded, interpolation can be carried out by utilizing the precedingand succeeding wobble reproduction signals. In this way, the position ofthe duplicate site 591 at the rewriting or at the time of additionalwriting has been set so as to be included in the non-modulation area590. Thus, there occurs advantageous effect that a stable wobbledetection signal from the wobble address information 610 can beguaranteed while preventing degradation of the wobble reproductionsignal amount due to the shape degradation in the wobble sync area 580or wobble address area 586.

Now, FIG. 85 shows an embodiment of a method for additionally writing awrite-once type data recorded on a write-once type information storagemedium. A position rearwardly of 24 wobbles is defined as a writingstart point from the boundary position of physical segment blocks. Withrespect to data to be newly additionally written, after a VFO area for71 data bytes has been formed, a data area (data field) in an ECC blockis recorded. This writing start point coincides with an end position ofthe buffer area 537 of recording data recorded immediately before thewriting. The backward position at which the expanded guard field 528 hasbeen formed by a length for eight data bytes is obtained as a recordingend position of additional writing data (writing end point). Therefore,in the case where data has been additionally written, the data for eightdata bytes is recorded to be duplicated at a portion of expanded guardfield 529 recorded just before and the VFO area to be newly additionallywritten.

Chapter 8: Description of B Format

Optical Disk Specification of B Format

FIG. 86 shows specification of an optical disk in a B format using ablue violet laser light source. The optical disks in the B format areclassified into rewritable-type (RE disk), read-only (ROM disk), andwrite-once type (R disk). However, as shown in FIG. 86, commonspecification other than standard data transfer speed is defined in anytype, facilitating the achievement of a drive commonly compatible with adifferent type. In a current DVD, two disk substrates having thicknessof 0.6 nm are adhered to each other. In contrast, a structure isprovided such that, in the B format, a recording layer is provided on adisk substrate having disk thickness of 1.1 nm, and the recording layeris covered with a transparent cover layer having thickness of 0.1 nm.

[Error Correction System]

In the B format, there is employed an error correction system capable ofefficiently sensing a burst error referred to as a “picket” code. A“picket” is inserted into main data (user data) patterns atpredetermined intervals. The main data is protected by strong, efficientReed Solomon codes. A “picket” is protected by second very strong,efficient Reed Solomon codes other than the main data. During decoding,a picket is first subjected to error correction. Correction informationcan be used to estimate a position of a burst error in the main data. Asa symbol of these positions, there is set a flag called “erasure”utilized when correcting a code word of the main data.

FIG. 87 shows a configuration of a “picket” code (error correctionblock). An error correction block (ECC block) of the B format isconfigured while the user data of 64 Kbytes is defined in unit in thesame manner as in the H format. This data is protected by very string,Reed Solomon codes LDC (long distance codes).

An LCD is formed of 304 cord words. Each code word is formed of 216information symbols and 32 parity symbols. Namely, a code word lengthhas 248 (=216+32) symbols. These code words are interleaved on a 2×2basis in a vertical direction of ECC blocks, configuring an ECC block ofhorizontal 152 (=304/2) bytes×vertical 496 (=2×216+2×32) bytes.

A picket interleave length has 155×8 bytes (there are eight correctionseries of control codes in 496 bytes), and a user data interleave lengthhas 155×2 bytes. The 496 types in the vertical direction are defined inunits of recording on a 31×31 row basis. With respect to the paritysymbols of the main data, two-groove parity symbols are provided asnests on a one by one row basis.

In the B format, picket codes padded at predetermined intervals havebeen employed for this ECC block in a “columnar” shape. A burst error issensed by referring to a state of that error. Specifically, four picketcolumns have been arranged at equal intervals in one ECC block. Anaddress is also included in a “picket”. A “picket” includes its uniqueparity.

There is a need for correcting symbols in the picket columns, and thus,the “pickets” in the right three columns are subjected to errorcorrection and encoding by means of BIS (burst indicator subcode), andis protected. This BIS is formed of 30 information symbols and 32 paritysymbols, and a code word length has 62 symbols. It is found that verystrong correction capability exists from a ratio between informationsymbols and parity symbols.

The BIS code word is interleaved and stored in three picket columns eachcomposed of 496 bytes. Here, the number of parity symbols per code wordwhich both of LDS and BIS codes have is equal to 32 symbols. Thisdenotes that LDC and BIS can be decoded by one common Reed Solomondecoder.

When data is decoded, first, a correcting process of picket columns iscarried out by means of the BIS. In this manner, a burst error locationis estimated, and a flag called “erasure” is set in that location. Thisflag is utilized when a code word of the main data is corrected.

The information symbols protected by the BIS codes forms additional datachannels (side channels) other than the main data. This side channelstores address information. Prepared executive Reed Solomon codes otherthan the main data are used for error correction of address information.This code is formed of five information symbols and four parity symbols.In this manner, it has been possible to grasp an address at a high speedand with a high reliability independent of an error correction system ofthe main data.

[Address Format]

In an RE disk, like a CD-R disk, a very thin groove is engraved as arecording track like a spiral. A recording mark is written into aprotrusive portion viewed in a laser light beam incident direction fromamong the irregularities (on-groove recording).

Address information indicating an absolute position on a disk is paddedby slightly wobbling (meandering or swinging) this groove like a CD-Rdisk or the like. Digital data for modulating signal is included, thedigital data indicating “1” or “0” in the shape or cycle of wobbling.FIG. 88 shows a wobble system. A wobbling amplitude is slightly ±10 nmin a disk radial direction. 56 wobbles (about 0.3 mm in disk length) isobtained as one bit of address information=ADIP unit (described later).

In order to write a fine recording mark without almost any displacement,it is necessary to generate a stable, precise recording clock signal.Therefore, attention has been paid to a system in which a main frequencycomponent of the wobbles is single and a groove is smoothly continuous.If the frequency is single, a stable recording clock signal can beeasily generated from a wobble component sampled by a filter.

Timing information or address information is added to a wobble on thebasis of this single frequency. “Modulation” is performed for thepurpose of this addition. For this modulation system, a system in whichan error is unlikely to occur is selected even if a variety ofvariations specific to an optical disk occur.

The following four variations of wobble signals generated in an opticaldisk are summarized on a factor by factor basis:

1) Disk noise: A variation in a surface shape which occurs with a grooveportion (surface roughness) at the time of manufacturing, noisegenerated in a recording film, and crosstalk noise leaks from recordeddata:

2) Wobble shift: A phenomenon that detection sensitivity is lowered by arelative shift of a wobble detection position from a normal position ina recording/reproducing apparatus. This shift is likely to occurimmediately after seek operation.

3) Wobble beat: A crosstalk generated between a track to be recorded anda wobble signal of the adjacent track. In the case where the rotationcontrol system is CLV (constant linear velocity), this beating occurs inthe case where a shift occurs with an angle frequency of the adjacentwobbles.

4) Defect: This is caused by a local defect due to the dust or scratchof a disk surface.

In an RE disk, two different wobble modulation systems are combined inthe form such that a synergetic effect is produced under a conditionthat high durability is provided with respect to all of these differentfour types of signal variations. In general, this is because thedurability relevant to four types of signal variations which is hardlyachieved by only one type of modulation system can be obtained withoutany side effect.

There are two systems: an MSK (minimum shift keying system; and an STW(saw tooth wobble) system (FIG. 89). The name of the STW comes from thefact that its waveform is like a saw tooth shape.

In the RE disk, one bit of “0” or “1” is expressed by a total of 56wobbles. These 56 wobbles are referred to as a unit, i.e., an ADIP(address inpre groove) unit. When the ADIP unit is continuously read outby 83 units, an ADIP word indicating one address is obtained. The ADIPword is formed of: address information having a 24-bit length; auxiliarydata having a 12-bit length; a reference (correction) area; and errorcorrection data. In the RE disk, three ADIP words per one RUB (recordingunit block, units of 64 Kbytes) for recording main data have beenarranged.

The DIP unit consisting of 56 wobbles is greatly divided into a firsthalf and a latter half. The first half whose wobble numbers range from 0to 17 is an MSK system; and the latter half whose wobble numbers rangefrom 18 to 55 is a STW system. These systems smoothly communicate with anext ADIP unit. One bit can be expressed by one ADIP unit. Depending onwhether “0” or “1” is set, first, in the first half, there is changed aposition of a wobble to which MSK system modulation is applied; and, inthe latter half, an orientation of a saw tooth shape is changed, therebymaking discrimination.

The first-half portion of the MSK system is divided into: a three-wobblearea in which MSK modulation has been further performed; and a mono-tonewobble cos (ωt) area. First, three wobbles from 0 to 2 always start fromat any ADIP unit to which MSK modulation has been applied. This isreferred to as a bit sync (identifier indicating start position of ADIPunit).

After this identifier has been passed, continuation of mono-tone wobblesis then obtained. Then, data is indicated according to how manymono-tone wobbles exist up to three wobbles which appear again next andwhich has been subjected to MSK modulation. Specifically, “0” is set inthe case of 11 wobbles, and “1” is set in the case of 9 wobbles. Data isdiscriminated from each other by means of a shift of two wobbles. TheMSK system utilizes a local phase change of a basic wave. In otherwords, an area in which no phase change occurs is dominant. In the STWsystem as well, this area is efficiently utilized as a location in whicha phase of a basic wave does not change.

An area to which MSK modulation has been applied has a three-wobblelength. A phase is restored by setting a frequency at 1.5 times withrespect to a mono-tone wobble at the first wobble; setting a frequencyequal to that of a mono-tone wobble at the second wobble; and setting afrequency at 1.5 times again at the third wobble. By doing this, thepolarity of the second (center) wobble is just inverted with respect tothe mono-tone wobble, and this inversion is detected. At the first startpoint and at the third end point, a phase is just fitted to a mono-tonewobble. Therefore, smooth connection free from a discontinuous portioncan be made.

On the other hand, there are two types of waveforms in the latter halfSTW system. One waveform rapidly rises toward the disk outer peripheryside and returns in gentle inclination to the disk center side, and theother waveform rises in gentle inclination, and returns rapidly. Theformer indicates data “0”, and the latter indicates data “1”. In oneADIP unit, the same bit is indicated by using both of the MSK system andthe STW system, thereby improving data reliability.

When the STW system is mathematically expressed, a secondary harmonicwave sin (2ωt) whose amplitude is ¼ is added to or subtracted from abasic wave cos (ωt). However, even whichever of “0” and “1” the STWsystem indicates, a zero cross point is identical to a mono-tone wobble.Namely, its phase is not affected at all when a clock signal is sampledfrom a basic wave component common to a mono-tone portion in the MSKsystem.

As described above, the MSK system and the STW system function so as tocompensate for weak points of counterparts each other.

FIG. 90 shows an ADIP unit. A basic unit of an address wobble forma isan ADIP unit. Each group of 56 NML (nominal wobble length) is referredto as an ADIP unit. One NML is equal to 69 channel bits. An ADIP unit ofa different type is defined by inserting a modulation wobble (MSK mark)into a specific position contained in an ADIP unit (refer to FIG. 89).83 ADIP units are defined as one ADIP word. A minimum segment of datarecorded in a disk precisely coincides with three continuous ADIP words.Each ADIP word includes 36 information bits (24 bits of which areaddress information bits).

FIGS. 91 and 92 each show a configuration of an ADIP word.

One ADIP word includes 15 nibbles, and nine nibbles are informationnibbles, as shown in FIG. 93. Other nibbles are used for ADIP errorcorrection. 15 nibbles configure a code word of Reed Solomon codes [15,9, 7].

A code word is formed of nine information nibbles; six informationnibbles record address information; and three information nibbles recordauxiliary information (for example, disk information).

Reed Solomon codes of [15, 9, 7] are non-systematic, and a hammingdistance due to “informed decoding” in knowledge in advance can beincreased. The “informed decoding” is such that all code words havedistance 7; all cod words of nibble no has distance 8 in common; andknowledge in advance relating to n₀ increases a hamming distance. Nibblen₀ is formed of an MSB of a layer index (three bits) and a physicalsector number. If nibble n₀ is known, distance increases from 7 to 8.

FIG. 94 shows a track structure. A description will be given here withrespect to a track structure of the first layer (which is distant from alaser light source) and the second layer of a disk having a single-sideddouble-layer structure. A groove is provided to enable tracking in apush-pull system. Plural types of track shapes are used. The first layerL₀ and the second layer L₁ are different from each other in trackingdirection. In the first layer, the left to the right of the figure is atracking direction. In the second layer, the right to the left is atracking direction. The left side of the figure is a disk innerperiphery, and the right side is an outer periphery.

A BCA (burst cutting area) area formed of a first-layer straight groove;a pre-recording area formed of an HFM (High Frequency Modulated) groove;and a wobble groove area in a rewritable area are equivalent to anH-format lead-in area. A wobble groove area in a second-layer rewritablearea; a pre-recording area formed of an HFM (High Frequency Modulated)groove; and a BCA area formed of a straight groove are equivalent to anH format lead-out area. However, in the H format, the lead-in area andthe lead-out area are recorded in a pre-pit system instead of a groovesystem. In the HFM groove, a phase is shifted in the first and secondlayers so as not to produce an inter-layer crosstalk.

FIG. 95 shows a recording frame. As shown in FIG. 87, the user data isrecorded on 64 by 64 Kbytes basis. Each row of the ECC cluster isconverted into the recording frame by adding frame sync bits and DCcontrol units. The stream of 1240 bits (155 bytes) in each row isconverted as follows. Data of 25 bits is arranged at the beginning ofthe 1240-bit stream, and the subsequent data is divided into data of 45bits; a frame sync code of 20 bits is added before data of 25 bits; oneDC control bit is added after data of 25 bits; and one DC control bit isadded after data of 45 bits similarly. A block including data of thefirst 2 bits is defined as DC control block #0, and the subsequent dataof 45 bits and one DC control bit are defined as DC control blocks #1,#2, . . . #27. 496 recording frames are referred to as a physicalcluster.

A recording frame is subjected to 1-7PP modulation at a rate of ⅔. Amodulation rule is applied to 1268 bits excluding the first frame synccode; 1902 channel bits are formed; and a frame sync code of 30 bits isadded at the beginning of the entirety. That is, 1932 channel bits (=28NML) are configured. A channel bit is subjected to NRZI modulation, andthe modulated bit is recorded in a disk.

Frame Sync Code Structure

Each physical cluster includes 16 address units. Each address unitincludes 31 recording frames. Each recording frame starts from a framesync code of 30 channel bits. The first 24 bits of frame sync codeviolates a 1-7PP modulation rule (including a length which is twice of 9T). The 1-7PP modulation rule uses a (1, 7) PLL modulation system tocarry out Parity Preserve/Prohibit RMTR (repeated minimum transition runlength). Parity Preserve makes control of a so called DC (directcurrent) component of a code (decreases a DC component of a code). Theremaining six bits of frame sync code changes, and identifies sevenframe sync codes FS0, FS1, . . . FS6. These six-bit signs are selectedso that a distance relating to a deflection amount is equal to orgreater than 2.

Seven frame sync codes make it possible to obtain more detailedpositional information than only 16 address units. Of course, it isinsufficient to identify 31 recording frames merely by seven differentframe sync codes. Therefore, from 31 recording frames, seven frame syncsequences are selected so that each frame can be identified by using acombination between one's own frame sync codes and a frame sync code ofeach of four preceding frames.

FIGS. 96A and 96B each show a structure of a recording unit block RUB. Arecording unit is referred to as a RUB. As shown in FIG. 96A, the RUB isformed of: 40-wobble data run-in; a physical cluster of 496×28 wobbles;and 16-wobble data run-out. Data run-in and data run-out enablessufficient data buffering in order to facilitate completely randomoverwriting. The RUB may be recorded on a one by one basis or aplurality of RUBs are continuously recorded as shown in FIG. 96B.

Data run-in is mainly formed of a repetition pattern of 3 T/3 T/2 T/2T/5 T/5 T, and two frame sync codes (FS4 and FS6) are spaced from eachother by 40 cbs as an indicator indicating a start position of a nextrecording unit block.

The data run-out starts at FS0, follows a 9 T/9 T/9 T/9 T/9 T/9 Tpattern which indicates the end of data after FS0, and follows arepetition pattern mainly formed of 3 T/3 T/2 T/2 T/5 T/5 T.

FIG. 97 shows a structure of data run-in and data run-out.

FIG. 98 is a view showing allocation of data relating to a wobbleaddress. A physical cluster is formed of 496 frames. A total of 56wobbles (NWLs) of data run-in and data run-out are 2×28 wobbles, andcorrespond to two recording frames.

One RUB=496+2=498 recording frames

One ADIP unit=56 NWLs=Two recording frames

83 ADIP units=One ADIP word (including one ADIP address)

Three ADIP words=3×83 ADIP units

Three ADIP words=3×83×2=498 recording frames

When data is recorded in a write-once disk, it is necessary tocontinuously record next data in already recorded data. If a gap occurswith data, reproduction cannot be carried out. Then, in order to record(overwrite) the first data run-in of the succeeding recording frame tobe overlapped on the last data run-out of the preceding recording frame,three guard areas are arranged at the end of the data run-out area, asshown in FIGS. 99A and 99B. FIG. 99A shows a case in which only onephysical cluster is recorded; and FIG. 99B shows a case in which aplurality of physical clusters are continuously recorded, wherein threeguard areas are provided only after run-out of the last cluster. Thus,each of the recording units recorded along, or alternatively, aplurality of recording unit blocks continuously recorded are terminatedin three guard areas. These three guard areas guarantees that anunrecorded area does not exist between the two recording unit blocks.

Now, a description will be given with respect to reproduction durabilityof a write-once type information storage medium according to anembodiment of the present invention. This storage medium includes atransparent resin substrate formed in a disk shape, the substrate beingmade of a synthetic resin material such as polycarbonate, for example.On this transparent resin substrate, a groove is formed in a concentricshape or in a spiral shape. This transparent resin substrate can bemanufactured by injection molding using a stamper.

In addition, on this transparent resin substrate, a recording filmincluding an organic dye is formed so as to fill its groove. An organicdye forming this recording film is used such that its maximum absorptionwavelength area is shifted to a longer wavelength side than a recordingwavelength (405 nm). In addition, absorption is not eliminated in arecording wavelength area, and a design has been made so as to havesubstantial light absorption.

In this manner, in the case where focusing or tracking is carried out ona track before information recording by means of a recording laser lightbeam, a low light reflectivity is obtained. A dye decomposing reactionis caused by the laser light beam, and the light absorbance is lowered,and thereby the light reflectivity of a recording mark portion rises.Thus, there are achieved so called a low-to-high (L to H) characteristicthat the light reflectivity of the recording mark portion formed byirradiating the laser light beam is higher than that before the laserlight irradiation.

In addition, a transparent resin substrate, and, in particular, a groovebottom may be deformed due to a heat generated. In this case, a phasedifference may occur with reflection light.

The above-described organic dye is liquefied by being solved in asolvent, and the liquefied dye can be easily applied onto a transparentresin substrate surface in accordance with a spin coat technique. Inthis case, film thickness can be managed with high precision bycontrolling a dilution rate based on a solvent or a rotation speed atthe time of spin coating.

The organic dye consists of a dye portion and an counter-ion (anion)portion. As the dye portion, a cyanine dye or a styryl dye and the likecan be used. In particular, the cyanine dye and the styryl dye arepreferred because absorbance relative to a recording wavelength iseasily controlled.

Referring to FIGS. 102A to 102E and 101A to 101C, a description will begiven with respect to a method for producing a disk stamper for awrite-once type storage medium.

As shown in FIG. 102A, there is prepared: a silicon wafer 2011 formanufacturing a semiconductor, the wafer being formed in a disk shape tohave a diameter of 200 nm and thickness of 0.725 mm.

This silicon wafer 2011 is immersed for 5 minutes in a mixture solutionof a thermal concentrated sulfuric acid and hydrogen peroxide water(solution temperature 100° C.). Next, the silicon wafer 2011 is rinsedby immersing it in ultra-pure water, and the rinsed wafer is washed withultrasound waves; the washed wafer is immersed in a 70° C. ultra-purewater tank, and the immersed wafer is dried by gradually pulling it up.

Then, as shown in FIG. 102B, an electron beam resist film 2012 is formedon a surface of the silicon wafer 2011. This electron beam resist film2012 is formed by spin-coating a resist solution obtained by mixing andstirring an electron beam resist (ZEP520A7 available from ZEONCorporation) by 86.2% by weight with respect to an anisole solvent(ZEP-A available from ZEON Corporation) on a surface of the siliconwafer 2011.

In addition, in a spin coating condition, the silicon wafer 2011 isvacuum-chucked on a spin table; a resist solution is dropped at thecenter part of the silicon wafer 2011 via a 0.1 micron filter whilerotation of the spin table stops; and then, the spin table is rotated at2500 rpm.

Then, as shown in FIG. 102 c, a groove 2013 is formed in the electronbeam resist film 2012. This is accomplished by putting the silicon wafer2011 coated with the electron beam resist film 2012 in a vacuum tankserving as an electron beam cutting machine; carrying out evacuation upto 10⁻⁵ Pa; and then, rotating the silicon wafer 2011; irradiating anelectron beam from an electron gun 2014 to the electron beam resist film2012; and carrying out electron-beam recording of a concentric or spiralgroove pattern.

A groove pattern recording condition is such that an electron beamacceleration voltage is 50 kV; a beam current is 120 nA; a beam diameteris 110 nm; and a recording beam linear speed is 1.1 m/sec. In arecording area of the groove 2013, the radius of the silicon wafer 2011ranges from 23 mm to 59 mm.

Then, the silicon wafer 2011 on which the groove 13 has been recorded isremoved from the inside of the vacuum tank serving as the electron beamcutting machine, and dip developing is carried out while the removedsilicon wafer is immersed in an organic developing solution 2016contained in an immersing tank 2015, as shown in FIG. 102D, therebyforming a resist pattern of the groove 2013.

Next, DC sputtering of an Ni film is carried out, and thereby an Ni thinfilm 2017 is formed and electrically conducted onto the above-describedresist pattern surface, as shown in FIG. 102E.

Then, as shown in FIG. 101A, Ni electric casting is carried out on theNi thin film 2017, forming an Ni-plated layer 2018 having thickness of247 μm. Then, as shown in FIG. 101B, the Ni-plated layer 2018 isreleased, and spin-coated, and then, the residual resin is released froma surface by means of oxygen RIE. Then, as shown in FIG. 101C, theNi-plated layer 2018 is coated with a protective film; a back face sidethereof is polished; an inner diameter and an outer diameter areprocessed; and a disk stamper 2019 is produced.

Next, a write-once type optical disk is produced by using this diskstamper 2019. That is, as shown in FIG. 100A, by using the disk stamper2019, injection molding is carried out by using an injection moldingdevice SD40 available from Sumitomo Heavy Industries Co., Ltd, therebyduplicating a transparent disk substrate 2020 made of polycarbonatehaving thickness of 0.6 mm as shown in FIG. 101B. A groove 2021 is, ofcourse, formed on this disk substrate 2020.

Then, as shown in FIG. 100C, by using a dispenser 2022 having a nozzlediameter of 21G, an organic dye solution 2023 described later obtainedby dissolving an organic dye in a solvent is dropped on a surface of thedisk substrate 2020 on which the groove 2021 is formed. Next, byrotationally controlling the disk substrate 2020, as shown in FIG. 100D,the groove 2021 is filled with the organic dye solution 2023, and arecording film 2024 is formed.

A spin coat condition of this recording film 2024, as shown in FIG. 103,is such that, first, the disk substrate 2020 is rotationally driven froman inactive state to 300 rpm within 1 second, and the organic dyesolution 2023 is coated by means of the dispenser 2022 while this stateis maintained for 8 seconds. Next, the rotation frequency of the disksubstrate 2020 is increased to 1800 rpm within 2 seconds, and this stateis maintained for 15 seconds. Then, the rotation frequency of the disksubstrate 2020 is increased to 3000 rpm within 2 seconds, and this stateis maintained for 3 seconds.

The film thickness of the recording film 2024 can be controlled bycontrolling the rotation speed at a second stage. More specifically, thefilm thickness of the recording film 2024 can be increased by settingthe rotation speed at the second stage at a low speed.

Next, the disk substrate 2020 coated with the recording film 2024 isbaked at 80° C. for 30 seconds by using a clean oven, and a 100 nm metalfilm 2025 is sputtered on the recording film 2024, as shown in FIG.100E. An Ag alloy including 1% of Bi in Ag is used as this metal film2025.

Then, as shown in FIG. 100F, an ultraviolet-ray curing type resin 2026is spin-coated on the metal film 2025, and a disk substrate 2027 made ofpolycarbonate having thickness of 0.6 mm is adhered onto the spin-coatedresin, and thereby a write-once type optical disk (R disk) 2028including an organic dye in the recording film 2024 is produced.

Here, in the write-once type optical disk 2028 produced as describedabove, a laser light beam for recording and reproduction by an opticalhead 2029 is made incident from a face opposite to a face coated withthe recording film 2024 of the disk substrate 2020, as shown in FIG.104.

In this case, a bottom face 2021 a of the groove 2021 formed on the disksubstrate 2020 and a land 2020 sandwiched between the adjacent grooves2021 are obtained as information recording tracks. The recording trackmade of the bottom face 2021 a of the groove 2021 is referred to as agroove track Gt, and the recording track made of the land 2030 isreferred to as a land track Lt.

In addition, a height difference between a face of the groove track Gtand a face of the land track Lt is referred to as a groove depth Gh.Further, a width of the groove track Gt viewed from a height which isalmost ½ of the groove depth Gh is referred to as a groove width Gw, anda width of the land track Lt viewed from a height which is almost ½ ofthe groove depth Gh is referred to as a land width Lw.

Now, a description will be given with respect to generation of theabove-described organic dye solution 2023. This organic dye solution2023 is used as a solution having a solution concentration of 1.2% byweight obtained by dissolving organic dye powders of 1.2 g in 100 nm ofTFP. A solution condition for a solvent is such that dye powders are putin the solvent, and ultrasound waves are applied for 30 minutes.

By using the organic dye, a write-once optical disk 2028 is produced bythe above-described method, and recording and reproduction are carriedout in these groove tracks Gt, thereby carrying out an evaluation test.As an evaluation device, an optical disk evaluation device availablefrom PULSTEC Co., Ltd is used.

A testing condition is such that an objective lens aperture NA of anoptical head is 0.65; a wavelength of a laser light beam for recordingand reproduction is 405 nm; and a linear velocity during recording andreproduction is 6.61 m/sec. A recording signal is 8-12 modulated randomdata, and is a waveform recorded by predetermined recording power andtwo types of bias powers 1 and 2 as shown in FIG. 105.

In addition, track pitches are 400 nm; a groove width Gw is defied as“1.2” with respect to a land width Lw “1”; a wobble amplitude of thegroove track Gt is 14 nm; and the groove depth Gh is 60 nm. Wobble phasemodulation is used to record address information using wobbles.

Here, three types of evaluation characteristics are measured including:a carrier noise ratio CNR of a reproduction signal; an SN ratio duringpartial response (partial response signal to noise ratio: PRSNR); and asimulated bit error rate SbER. PRSNR defining and measuring techniquesare described in a book which can be purchased from DVD Format LogoLicensing Co., Ltd. This is a part of Annex H of DVD Specifications forHigh Density Read-Only Disc PART 1 Physical Specifications Version 1.0.It is preferable that the PRSNR be 15 or more. The SbER defining andmeasuring techniques are described in a book which can be purchased fromDVD Format Logo Licensing Co., Ltd. This is a part of Annex H of DVDSpecifications for High Density Read-Only Disc PART 1 PhysicalSpecifications Version 1.0. It is preferable that the SbER be 5.0×10⁻⁵or less. The PRSNR and SbER are measured in a state in which informationis recorded in the adjacent tracks.

As evaluation characteristics, three types of light reflectivity, SbER,and PRSNR are measured. A light reflectivity defining and measuringtechniques are described in a book which can be purchases from DVDFormat Logo Licensing Co., Ltd. This is a part of Annex D of DVDSpecifications for High Density Read-Only Disc PART 1 PhysicalSpecifications Version 1.0. The reflectivity corresponds to I11H levelafter recording. It is preferable that the reflectivity range from 14%to 28% in order to obtain reproduction light durability of 1,000,000times or more.

In addition, in the case where management information (system lead-in)is inserted into a certain portion of a disk, for example, into theinnermost peripheral area, the most advantageous effect can be attainedin this Low-to-High recording disk. With respect to managementinformation, pit arrays identical to those on a ROM disk substrate areformed on a disk substrate. What is recorded as a pit array ismanagement information such as whether the disk is a read-only type orwrite-once type, or rewritable type; what recording and reproducingwavelength is, whether the recording film type is Low-to-High orHigh-to-Low, and what a recording data capacity is. The track pitches ofa groove of a recording data area are selected as 400 nm or in the rangeof 320 nm to 300 nm. Advantageously, the track pitches of the pit arrayin this management information area is formed to be wider than the abovetrack pitches, and data bit pitches of pits are larger than that of therecording data area, thereby facilitating reproduction and making itpossible to easily judge management information. The Low-to-High disk isuniform in signal level position between a system lead-in area and adata area, and drive reproduction is made easy.

Now, a description will be given with respect to a test result relatingto reproduction durability count in the case where a mark recorded in anoptical disk using an organic dye material according to the presentinvention for a recording material has been continuously reproduced by ablue laser light beam pickup. Here, testing has been carried out withrespect to 5 types of organic dye materials.

A first material is dye “A” which is an organic metal complex simplex,and a general structural formula of Al which is an example of the dye isshown in FIG. 106. Cu, Zn, Ni, Co, Fe, Sc, Ti, V, Cr, Mn, Al, Gd, and Yor the like are mainly used as M. Cu is the best in reproduction lightdurability.

As R1 to R5, there are used CH₃, C₂H₅, H, CH₂N(CH₃)₂, SCH₃, NO₂, Cl,SO₂NHCH₃, CN, and CH₃OCH₂ or the like without being limited thereto. Inparticular, in the case where Cl has been added, the best reproductionlight durability is obtained.

In an example A1 of dye “A”, M is Cu; R1 is CH₃; R2 is CH₃; R3 is CH₃;R4 is Cl; and R5 is Cl.

A second material is dye B which is an organic metal complex simplexhaving another structure, and a general structural formula of B1 whichis an example of the dye is shown in FIG. 107. Cu, Zn, Ni, Co, Fe, Sc,Ti, V, Cr, Mn, Al, Gd, and Y or the like are mainly used as M. Cu is thebest in reproduction light durability.

As R1 to R5, there are used CH₃, C₂H₅, H, CH₂N(CH₃) 2, SCH₃, NO₂, Cl,SO₂NHCH₃, CN, and CH₃OCH₂ or the like without being limited thereto. Inparticular, in the case where Cl has been added, the best reproductionlight durability is obtained.

In an example B1 of dye B, M is Cu; R1 is C₂H₅; R2 is CH₃; R3 is C₂H₅;R4 is SCH₃; and R5 is Cl.

B1 is better than A1 in PRSNR and SbER when it is used for an opticaldisk; and is better in recording and reproducing characteristics such aslarge degree of modulation and high reflectivity.

A third dye is a mixture dye made of an organic metal complex cation andanion U composed of cation and an organic metal complex anion; anorganic metal complex cation and anion W composed of cation and anorganic metal complex anion; and an organic metal complex simplex Y, andis a mixture of dye U1, dye W1, and dye Y2. An azo phthalocyanine metalcomplex has been used as Y. A general structural formula of U, a generalstructural formula of W, and a general structural formula of Y are shownin FIG. 108, FIG. 109, and FIG. 110, respectively.

Here, a cation portion in FIG. 108 is a monomethine cyanine dye, and ananion portion in FIG. 108 is an organic metal complex.

In addition, with respect to the above-described monomethine cyaninedye, Z₁ and Z₂ represent aromatic rings which are identical to ordifferent from each other, and these aromatic rings may havesubstituents. Y₁₁ and Y₁₂ each represent a carbon atom or a hetero atomindependently. R₁₁ and R₁₂ each represent an aliphatic hydrocarbongroup, and these aliphatic hydrocarbon groups may have substituents.R₁₃, R₁₄, R₁₅, and R₁₆ each represent a hydrogen atom or an appropriatesubstituent independently. In the case where Y₁₁ and Y₁₂ are heteroatoms, part or all of R₁₃, R₁₄, R₁₅, and R₁₆ do/does not exist.

In addition, in the above-described organic metal complex, A and A′represent heterocyclic groups which are identical to or different fromeach other, the groups each containing one or a plurality of heteroatoms selected from a nitrogen atom, an oxygen atom, a sulfur atom, aselenium atom, and a tellurium atom. R₂₁ to R₂₄ each represent ahydrogen atom or a substituent independently. Y₂₁ and Y₂₂ each representhetero atoms which are identical to or different from each other, theatoms each being selected from elements of a sixteenth family in theperiodic table.

Monomethine cyanine dyes used in the present embodiment can include dyesobtained when cyclic nucleuses such as an imidazoline ring; an imidazolering; a benzoimidazole ring; an α-naphthoimidazole ring; aβ-naphthoimidazole ring; an indole ring; an isoindole ring; an indoreninring; an isoindorenin ring; a benzo indorenin ring; a pyridino indoreninring; an oxazolline ring; an ozazole ring; an isoozazole ring; abenzooxazole ring; pyridino oxazole ring; an α-naphtooxazole ring; aβ-naphthoozazole ring; a serenazoline ring; a serenazole ring; abenzoserenazole ring; an α-naphthoserenazole resin; aβ-naphthoserenazole ring; a thiazoline ring; a thiazole ring; anisothiazole ring; a benzothiazole ring; an α-naphthothiazole ring; aβ-naphthothiazole ring; a terrazoline ring; a terrazole resin; abenzoterrazole ring; an α-naphthoterrazole ring; a β-naphthoterrazolering; and further, an acrydine ring; an antracen ring; an isoquinolinering; an isopyrole ring; an imidanoxaline ring; an indandione ring; anindazole ring; an indaline ring; an oxadiazole ring; a carbazole ring: axantene ring; a quinazoline ring; a quinoxaline ring; a quinoline ring;a chroman ring; a cyclohexane dione ring; a cyclopentane dione ring; acinnoline ring; a thiodiazole ring; a thiooxazolidone ring; a thiophenering; a thionaphthene ring; a thiobarbizuric acid ring; a thiohidantoinring; a tetrazole resin; a triazine ring; a naphthalene ring; anaphthyridine ring; a piperadine ring; a pyradine ring; a pyrazole ring;a pyrazoline ring; a pyrazolidine ring; a pyrazolone ring; a pyranering; a pyridine ring; a pyridazine ring; a pyrimidine ring; a pyriliumring; a pyrolidine ring; a pyroline ring; a pyrol ring; a phenedinering; a phenantholidine ring; a phenanthorene ring; a phenanthorolinering; a phthaladine ring; a putheridine ring; a phrazane ring; a phranering; a purine ring; a benzene ring: a benzooxadine ring; a benzopiranering; a morpholine ring; and a rhodaline ring or the like, which areidentical to or different from each other, having one or a plurality ofsubstituents, are bonded on both ends of a monomethine chain which mayhave one or a plurality of substituents.

In addition, through general formulas of the monomethine cyanine dye, Z1to Z3, for example, represent aromatic rings such as a benzene ring, anaphthalene ring, a pyridine ring, a quinoline ring; and a quinoxalinering or the like, and these aromatic rings may have one or a pluralityof substituents. The substituents, for example, can include: aliphatichydrocarbon groups such as a methyl group, a trifluoro methyl group, anethyl group, a propyl group, an isopropyl group, a butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group,an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylpentyl group, a 2-methyl pentyl group, a hexyl group, an isohexyl group,a 5-methyl hexyl group, a heptyl group, and an octyl group;cycloaliphatic hydrocarbon groups such as a cyclopropyl group, acyclobutyl group, a cyclopentyl group, and a cyclohexyl group; aromatichydrocarbon groups such as a phenyl group, a biphenyl group, an o-trylgroup, an m-tryl group, a p-tryl group, a xyryl group, a mecityl group,an o-cumenyl group, an m-cumenyl group, a p-cumenyl group; ether groupssuch as a methoxy group, a trfluoro methoxy group, an ethoxy group, apropoxy group, an isopropoxy group, a buthoxy group, a sec-buthoxygroup, a tert-buthoxy group, a pentyloxy group, a phenoxy group, abenzoir oxy group; ester groups such as a methoxycarbonyl group, atrifluoro methoxycarbonyl group, an ethoxycarbonyl group, apropoxycarbonyl group, an acetoxy group, and a benzoir oxy group;halogen groups such as a fluoro group, a chloro group, a bromo group,and an iodine group; thio groups such as a metylthio group, an ethylthiogroup, propylthio group, butylthio group, and a phenylthio group;sulfurmoyl groups such as a methyl sulfurmoyl group, a dimethylsulfurmoyl group, an ethyl sulfurmoyl, a diethyl sulfurmoyl group, apropyl sulfurmoyl group, a dipropyl sulfurmoyl group, a butyl sulfurmoylgroup, and a dibutyl sulfurmoyl group; amino groups such as a firstclass amino group, a methyl amino group, a dimethyl amino group, anethyl amino group, a diethyl amino group, a propyl amino group, adipropyl amino group, an isopropyl amino group, a diisopropyl aminogroup, a butyl amino group, a dibutyl amino group, and a pyperidinogroup; carbamoyl groups such as a methyl carbamoyl group, a dimethylcarbamoyl group, an ethyl carbamoyl group, a diethyl carbamoyl group, apropyl carbamoyl group, and a dipropyl carbamoyl group; and further, ahydroxy group, a carboxy group, a cyano group, a nitro group, a sulfinogroup, a sulfo group, and a mecyl group or the like. In a generalformula, Z₁ and Z₂ may be identical to or differential from each other.

Y₁₁ and Y₁₂ in a general formula of a monomethine cyanine dye eachrepresent a carbon atom or a hetero atom. Hetero atoms, for example, caninclude atoms of a fifteenth family and a sixteenth family in theperiodic table such as a nitrogen atom, an oxygen atom, a sulfur atom, aselenium atom, or a tellurium atom. The carbon atoms in Y₁₁ and Y₁₂ maybe an atom group consisting essentially of two carbon atoms such as anethylene group and a vinylene group, for example. Y₁₁ and Y₁₂ in thegeneral formula of the monomethine cyanine dye may be identical to ordifferent from each other.

R₁₁, R₁₂, and R₁₃ in the general formula of the monomethine cyanine dyerepresent aliphatic hydrocarbon groups. Example of the aliphatichydrocarbon groups can include: a methyl group; an ethyl group; a propylgroup; an isopropyl group; an isopropenyl group; a 1-propenyl group; a2-propenyl group; a butyl group; an isobutyl group; a sec-butyl group; atert-butyl group; a 2-butenyl group; a 1, 3-butadinyl group; a pentylgroup; an isopentyl group; a neopentyl group; a tert-pentenyl group; a1-methyl pentyl group; a 2-methyl pentyl group; a 2-pentenyl group; ahexyl group; an isohexyl group; a 5-methyl hexyl group; a heptyl group,and an octyl group or the like. The aliphatic hydrocarbon groups mayhave one or a plurality of substituents similar to those in Z₁ to Z₃.

In addition, R₁₁ and R₁₂ in the general formula of the monomethinecyanine dye may be identical to or different from each other.

R₁₃ to R₁₆ in the general formula of the monomethine cyanine dye eachrepresent hydrogen atoms or proper substituents independently inindividual general formulas. The substituents, for example, include:aliphatic hydrocarbon groups such as a methyl group, a trifluoro methylgroup, an ethyl group, a propyl group, an isopropyl group, a butylgroup, an isobutyl group, a sec-butyl group, a tert-butyl group, apentyl group, an isopentyl group, a neopentyl group; a tert-pentylgroup, a 1-methyl pentyl group, a 2-methyl pentyl group, a hexyl group,an isohexyl group, a 5-methyl hexyl group, a heptyl group and a octylgroup; ether groups such as a methoxy group, a trifluoro methoxy group,an ethoxy group, a propoxy group, buthoxy group, a tert-buthoxy group, apentyl oxy group, a phenoxy group, and a benxoir oxy group; halogengroups such as a fluoro group, a chloro group, a bromo group, and aniodine group; and further, a hydroxy group; a carboxy group; a cyanogroup; and a nitro group or the like. In the general formula of themonomethine cyanine dye, in the case where Y₁₁ and Y₁₂ are hetero atoms,part or all of R₁₃ to R₁₆ in Z₁ and Z₂ do/does not exist.

In addition, in the general formula of the above-described azo metalcomplex, A and A′ each represent heterocyclic groups of five rings toten rings such as a furyl group, a thienyl group, a pyroryl group, apyridyl group, a pypelidino group, a pypelizyl group, a quinoryl group,and an isooxazoryl group, for example, which are identical to ordifferent from each other and contain one or a plurality of hetero atomsselected from among a nitrogen atom, an oxygen atom, a sulfur atom, aselenium atom, and a tellurium atom. These heterocyclic groups, forexample, may have one or a plurality of aliphatic hydrocarbon groupssuch as a methyl group, a trifluoro methyl group, an ethyl group, apropyl group, an isopropyl group, a butyl group, an isobutyl group, asec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group,a neopentyl group, a tert-pentyl group, a 1-methyl pentyl group, a2-methyl pentyl group, a hexyl group, an isohexyl group, and a 5-methylhexyl group; ester groups such as a methoxy carbonyl group, a trifluoromethoxy carbonyl group, an ethoxy carbonyl group, a propoxy carbonylgroup, an acetoxy group, a triflyoro acetoxy group, and benzoir oxygroup; aromatic hydrocarbon groups such as a phenyl group, a biphenylgroup, an o-tryl group, an m-tryl group, a p-tryl group, an o-cumenylgroup, an m-cumenyl group, a p-cumenyl group, a xyryl group, a mecitylgroup, a styryl group, a cinnamoyl group, and a naphtyl group; andfurther, substituents such as a carboxyl group, a hydroxy group, a cyanogroup, and a nitro group.

An azo compound configuring an azo-based organic metal complexrepresented by a general formula can be obtained in accordance with anormal technique by reacting a diazonium salt having R₂₁, R₂₂ or R₂₃,R₂₄ which corresponds to the general formula with heterocyclic compoundssuch as an isooxazolone compound, an oxazolone compound, a thionaphthenecompound, a pyrazolone compound, a barbizuric acid compound, a hydantoincompound, and a rhodanine compound or the like, for example, having anactive methylene group adjacent to a carbonyl group in a molecule. Y₂₁and Y₂₂ each represent hetero atoms which are identical to or differentfrom each other, the atoms being selected from elements of the sixteenthfamily in the periodic table such as an oxygen atom, a sulfur atom, aselenium atom, and a tellurium atom, for example.

The azo metal complex represented by the general formula is generallyused in a mode in which one or a plurality of metal complexes areoriented at a metal (center atom). Examples of metal elements serving asthe center atoms, for example, can include scandium, yttrium, titanium,zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum,tungsten, manganese, technetium, rhenium, iron, lutenium, osmium,cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver,gold, zinc, cadmium, and mercury or the like. In particular, cobalt ispreferred. X² in the general formula represents a proper anodic ionincluding an onium ion such as alkyl ammonium ion, a pyridinium ion, andquinolinium ion, for example.

As M of the azo phthalocyanine complex Y, there is used any of Cu, Ni,Al, Zn, Y, Co, Fe, Sc, Ti, V, Cr, and Mn. In particular, Cu is the bestin reproduction light durability.

As R, there is used CH₃, C₂H₅, H, CH₂N(CH₃)₂, SCH₃, NO₂, C₁, SO₂NHCH₃,CN, CH₃OCH₂, and SO₃H or the like without being limited thereto. Inparticular, in the case where Cl is added, the reproduction lightdurability is good.

Structural formulas of U1 which is an example of U, W1 which is anexample of W, and Y2 are shown in FIG. 111 and FIG. 112.

With respect to Y2 which is an example of Y, Ni is selected as M, andNO₂ is selected as R.

A mixture ratio by weight of U, W, and Y is 1.0:2.0:0.15.

If a formazane metal complex V is used instead of Y2, a similar dye isobtained. A structural formula of V is shown in FIG. 113.

A fourth dye is a mixture dye of an organic metal complex B; an organicmetal complex cation and anion W composed of cation and an organic metalcomplex anion; and an organic metal complex simplex Y, and is a mixtureof dye B1, dye W2, and dye Y1. An axo phthalocyanine metal complex wasused as Y. A general structural formula of W2 which is an example of Wis shown in FIG. 114.

In Y1 which is an example of Y, Cu is selected as M, and Cl is selectedas R.

A mixture ratio by weight of B, W, and Y is 0.7:0.3:0.15.

A fifth dye is a mixture dye of an organic metal complex cation andanion U composed of cation and an organic metal complex anion; anorganic metal complex cation and anion W composed of cation and anorganic metal complex anion; and an organic metal complex simplex Y, andis a mixture of dye U1, dye W1, and dye Y2. An azo phthalocyanine metalcomplex has been used as Y. A mixture ratio by weight of U, W, and Y is1.0:2.0:0.15.

In addition to these examples, as an organic metal complex anion andcation, there can be used general structural formulas such as WW shownin FIG. 115; WWW shown in FIG. 116; and WWWW shown in FIG. 117. As anexample of WW, WW1 is shown in FIG. 118; as an example of WWW, WWW1 isshown in FIG. 119; and as examples of WWWW, WWWW1 and WWWW2 are shown inFIG. 120 and FIG. 121. In the general formula of the organic metalcomplexes WW, WWW, and WWWW, A an A′ each represent heterocyclic groupsof five to ten rings such as a furyl group, a thienyl group, a pyrrolylgroup, a pyridyl group, a pyperidino group, pyperidyl group, a quinorylgroup, and isooxazoryl group, for example, which are identical to ordifferent from each other, the groups each containing one or a pluralityof hetero atoms selected from a nitrogen atom, an oxygen atom, a sulfuratom, a selenium atom, and a tellurium atom. These heterocyclic groups,for example, may have one or a plurality of aliphatic hydrocarbon groupssuch as a methyl group, a trifluoro methyl group, an ethyl group, apropyl group, an isopropyl group, a butyl group, an isobutyl group, asec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group,a neopentyl group; a tert-pentyl group, a 1-methyl pentyl group, a2-methyl pentyl group, a hexyl group, an isohexyl group, and a 5-methylhexyl group; ester groups such as a methoxy carbonyl group, a trifluoromethoxy carbonyl group, an ethoxy carbonyl group, a propoxy carbonylgroup, an acetoxy group, a trifluoro acetoxy group, and benzoir oxygroup; aromatic hydrocarbon groups such as a phenyl group, a biphenylgroup, an o-tryl group, an m-tryl group, a p-tryl group, an o-cumenylgroup, an m-cumenyl (group, a p-cumenyl group, a xyryl group, a mecitylgroup, a styryl group, a cinnamoyl group, and a naphtyl group; andfurther, substituents such as a carboxy group, a hydroxy group, a cyanogroup, and a nitro group.

A compound configuring an organic metal complex represented by a generalformula can be obtained in accordance with a normal technique byreacting a diazonium salt having R, R21, R32, R33, R34, R41, and R42which correspond to the general formula with heterocyclic compounds suchas an isoozazolone compound, an oxazolone compound, a thionaphthenecompound, a pyrazolone compound, a barbizuric acid compound, a hydantoincompound, and a rhodain compound, for example, having an activemethylene group which is adjacent to a carbonyl group in a molecule.Y31, Y32, Y41, Y42, and Y represent hetero atoms which are identical toor different from each other, the atoms being selected from elements ofthe sixteenth family in the periodic table such as an oxygen atom, asulfur atom, a selenium atom, and a tellurium atom, for example.

The organic metal complex represented by the general formula isgenerally used in a mode in which one or a plurality of metal complexesare oriented at a metal (center atom). Examples of metal elementsserving as the center atoms, for example, can include scandium, yttrium,titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium,molybdenum, tungsten, manganese, technetium, rhenium, iron, lutenium,osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper,silver, gold, zinc, cadmium, and mercury or the like. X² in the generalformula represents a proper anodic ion including an onium ion such asalkyl ammonium ion, a pyridinium ion, and quinolinium ion, for example.

A test for reproduction degradation was carried out by recording an ETMmodulation signal in a write-once type R optical disk fabricated byusing the above 5 types of organic dye materials, and then, obtainingreproduction count when a degree of signal modulation is 0.4 or less,PRSNR is 15 or less, and SbER is 5×10⁻⁵ or more in the case where atrack recorded by predetermined reproduction laser power wascontinuously reproduced (still-reproduced) at a line speed of 6.61m/sec. The reproduction light stability is better as the reproductioncount increases. A result is shown in FIG. 122. It was found that thereproduction durability count is 1,000,000 or more at the reproductionlaser power of 0.4 mW in an “L to H” type optical disk using a mixturedye. Namely, it was found that a mixture of a plurality of an organicmetal complex simplex and an organic metal complex cation and anion hasexcellent reproduction light durability. In particular, the fifthmixture dye of two types of organic metal complex cation and anion andan organic metal complex simplex achieved 1,500,000 or more inreproduction light durability.

In addition, with respect to the reflectivity obtained by measuring I11Hafter recording, the reflectivity was 12% in the case of the first dye“A” and 30% in the case of the second dye. The reflectivity was 14% inthe case of the third dye U+W+Y; the reflectivity was 22% in the case ofthe fourth dye B+W+Y; and the reflectivity was 28% in the case of thefifth dye U+W+Y. Therefore, it was experimentally found convenient thatthe reflectivity ranges from 14% to 28% in order to obtain thereproduction light durability of 1,000,000 times or more.

In addition, a novel embodiment that the following concept ofconstitution of a mixture dye is proper was obtained. This constitutionconsists of at least two portions, i.e., a “recording function dye” anda “reproduction light durability function dye”. An organic metal complexsuch as A, B, or Y can be used as the former “recording function dye”.The organic metal complex is not limited to these structures orskeletons. In addition, U, V, W, WW, WWW, and WWWW can be used. Use ofan anion and cation type is convenient to further improve reproductionlight durability. Mainly, it is preferable to use a dye of this portionhaving excellent performance of recording and reproducingcharacteristics. The latter “reproduction light durability function dye”serves to improve the reproduction light durability. Although the use ofone type of the dye will suffice, the use of two types is furthereffective. An organic metal complex such as A, B, or Y can also be used.The organic metal complex is not limited to these structures andskeletons. In addition, U, V, W, WW, WWW, and WWWW can be used. The useof a cation and anion type is convenient to further improve thereproduction light durability. In particular, the use of dyes W, WW,WWW, and WWWW is preferable to improve the reproduction lightdurability. For example, in the case where two types are used, it isconvenient to carry out recording of a burst cutting area (BCA) byadjusting a maximum absorption wavelength of one dye in the range of 630nm to 680 nm, and large BCA amplitude can be obtained. In the case wherea high level voltage (IBH) of a BCA signal is set to 100%, it becomespossible to set the BCA signal amplitude to 20% or more. IBL/IBH can beset to 0.80 or less when this amplitude is expressed by using a lowlevel voltage (IBL).

In addition, with respect to a mixture ratio of the “recording functiondye” and the “reproduction light durability function dye”, it ispreferable that the “reproduction light durability function dye” rangefrom 30% to 400% in the case where the “recording function dye” is setto 100%. It is particularly preferable that the above dye range from150% to 300%. The best ratio should be set to 200%. It is preferablethat a dye added for BCA recording range from 5% to 50%. It isparticularly preferable that the dye range from 10% to 30%. The bestratio should be set to 15%.

The present invention is not limited to the above-described embodiments.At a stage of carrying out the invention, the present invention can beembodied by modifying constituent elements without departing from thespirit of the invention. In addition, a variety of inventions can beformed by using a proper combination of a plurality of constituentelements disclosed in the above-described embodiments. For example, someconstituent elements may be eliminated from all the constituent elementsshown in the embodiments. Further, the constituent elements over thedifferent embodiments may be properly combined with each other.

EXAMPLES

Now, examples of the recording film will be described here. In thefollowing examples, one-sided single layer mediums and one-sided doublelayer mediums were fabricated. As a substrate, there was used apolycarbonate (PC) substrate having thickness of 0.6 mm (fabricated byinjection molding. A groove was formed on the substrate in track pitchesof 0.4 μm. A one-sided single layer medium was fabricated as follows.That is, a dye was coated on the substrate in accordance with a spincoat technique. On the coated substrate, a reflection layer was formedin a sputtering technique. On the formed reflection layer, a PCsubstrate having thickness of 0.6 mm was adhered by using an UV curingresin.

On the other hand, two methods can be used in the case of the one-sideddouble layer medium. In a first method, the one-sided double layermedium was fabricated as follows. On an L0 substrate, a dye was coatedin accordance with a spin coat technique. On the coated substrate, asemipermeable reflection layer was formed in accordance with asputtering technique. On the formed layer, an interlayer separatinglayer and a groove for L1 were formed in accordance with a 2P technique(photo polymer technique). Further, on the formed groove, a dye wascoated again in accordance with the spin coat technique. On the coatedlayer, a reflection layer was formed in accordance with the sputteringtechnique. Lastly, a PC substrate having thickness of 0.6 mm was adheredto the formed reflection layer by using a UV curing resin. In thismethod, the L0-layer semipermeable reflection film was formed, andfurther, another layer can be formed on the formed reflection film foradjustment of optical characteristics. In a second method, the followingpreparation was carried out. On an L0 substrate, a dye was coated inaccordance with a spin coat technique. On the coated substrate, asemipermeable reflection layer was formed in accordance with asputtering technique. In addition, on the L1 substrate, first, areflection layer is formed in accordance with a sputtering technique. Onthe formed reflection layer, a dye was coated in accordance with a spincoat technique. The fabricated L0 and L1 substrates were adhered to eachother using a UV curing resin while their respective semipermeablereflection film and organic dye film were set inwardly. In this method,another layer can be inserted between an organic dye layer which is arecording layer of L1 and the UV curing resin for the purpose ofstabilizing an organic dye which is a recording film material of L1 oradjusting optical characteristics. In the present embodiment, testingwas carried out using mediums fabricated by both of the methods.

For evaluation, a disk evaluation device ODU-1000 available from aPULSTEC Co., Ltd. was used. This device includes a blue violetsemiconductor laser having a wavelength of 405 nm and an objective lensof NA=0.65. Recording and reproducing testing was carried out under acondition for a linear velocity of (6.6 m/sec. Evaluation was carriedout with respect to five characteristics below. That is, measurements of(a) SbER (Simulated bit Error Rate); (b) PRSNR (Partial Response Signalto Noise Ratio); (c) Modulation; (d) reflectivity of data portion; and(e) read stability of each storage medium were carried out. Theevaluation criteria were defined as follows. That is, in the case wherecontinuous readout is carried out at an SbER of 5.0×10⁻⁵ or less, aPRSNR of 15.0 or more, a modulation of 0.4 or more, a reflectivity of14% or more in the case of a one-sided single layer medium or areflectivity of 4% or more in each of the L0 and L1 mediums in the caseof one-sided double layer, at power of 0.4 mW in the case of a one-sidedsingle layer medium and at any good power of 0.4 mW to 0.8 mW in thecase of a one-sided double layer medium for read stability, even ifreadout was carried out for 1,000,000 times or more, characteristics (a)to (e) must achieve their target values. Read power in the one-sideddouble layer medium was selected as a condition such that SN ratios andsignal amplitudes of reproduction signals are substantially equal toeach other in L0 and L1. This is because optical characteristics (L0reflectivity and transmittance, L1 reflectivity) and sensitivity of amedium and a signal amplitude and SN ratio of reflection signal aredifferent depending on a dye of a medium and a material (and a filmthickness or the like of the reflection film. However, the read powervalues of L0 and L1 are often identical to each other. In the case whereall the characteristics met the target values, the storage medium wasdefined as “good”, and if only one characteristic failed to meet itstarget value, the medium was defined as being “unacceptable”.

There were used three types of organic dye recording materials(occasionally simply referred to as dye), i.e., (1) cation-anion based;(2) organic metal complex (azo based); and (3) mixture dye ofcation-anion based and organic metal complex (azo based). The usedreflection films are binary Ag allows, i.e., AgAu, AgBi, AgCa, AgCe,AgCo, AgGa, AgLa, AgMg, AgN, AgNi, AgNd, AgPd, AgY, AgW, AgZr; andtertiary Ag alloys, i.e., AgAlMg, AgAuBi, AgBiGa, AgAuCo, AgAuCe,AgAuNi, AgAuMg, AgBiMg, AgBiN, AgBiPd, and AgBiZr; and advantageouseffect in the case where additive elements of group 1 and group 2 and N(nitrogen) were added at the same time was verified. As a film formingmethod, there was used each of Ag alloy targets described previously orthere was used a multi-dimensional simultaneous sputtering in which asputtering condition was adjusted so as to obtain a desiredconstitution. Reaction with nitrogen was carried out by using as asputtering gas a mixture gas of Ar and N (nitrogen) instead of only Ar.The constitution, film thickness, and substrate shape of dyes andreflection films were adjusted, respectively, so that signalcharacteristics are good.

Additive amounts of additive elements in an Ag alloy reflection filmused in each of examples were four levels of 0.05 at %, 1 at %, 2 at %,and 5 at %, and three levels of (1), (2), and (3) were used for organicdye materials. Therefore, a total number of sample types produced inexamples were 12. FIG. 123 and FIG. 124 each show additive element namesof Ag-alloy reflection films used in examples, and FIG. 125 showsAg-alloy reflection films and amounts of additive elements used incomparative examples and a chart of combination with organic dyematerials. As organic dye material (4), there was used a conventionallyused dye material, i.e., a phthalocyanine based organic dye andsuper-green dye (IRAPHOR Utragreen MX available from Ciba SpecialityChemicals).

Example 1

In example 1, a one-sided single layer storage medium was produced, andtesting was carried out. Au was used as an additive element of anAg-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at% were used as additive amounts; and three types (1), (2), and (3) wereused as organic dye materials for recording films. In order to cover allcombinations of amounts of additive elements and dye materials, allcombinations, 12 types of storage mediums were produced, and evaluationof the recording and reproducing characteristics were carried out. FIG.126 specifically exemplifies constitutions of reflection films andcombinations of organic dye materials for recording films.

When the characteristics (a) to (e) of the produced storage mediums wereevaluated, the evaluation results were obtained as shown in FIG. 127.

As is evident from these results, each of the storage mediums achievedthe target values; SbER of 5.0×10⁻⁵ or less; PRSNR of 15.0 or more;modulation of 0.4 or more; reflectivity of 14% or more; and readstability of 1,000,000 times or more. Therefore, each of the storagemediums obtained “good” characteristics.

Example 2

In example 2, one-sided single layer and double layer storage mediumswere produced. Bi was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) was usedas organic dye materials for recording films. As in example 1, 12combinations of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. With respectto the one-sided double layer storage medium, a medium whose Bi additiveamounts are 0.05 at % and 1 at % was produced, and with respect to theone-sided single layer storage medium, a medium whose Bi additiveamounts are 1 at %, 2 at %, and 5 at % was produced, respectively, andevaluation was carried out. FIG. 128 specifically exemplifiesconstitutions of reflection films and combinations of organic dyematerials for recording films.

When the characteristics (a) to (e) of the produced storage mediums wereevaluated, the evaluation results were obtained as shown in FIG. 129. InFIG. 129, data represented with “double layer” indicates data on aone-sided double layer medium in the case where there exists data onboth of a one-sided single layer medium and a one-sided double layermedium.

As is evident from these results, each of the storage mediums achievedthe target values; SbER of 5.0×10⁻⁵ or less; PRSNR of 15.0 or more;modulation of 0.4 or more; reflectivity of 4% or more relevant to theone-sided double layer medium in both of L0 and L1 and 14% or morerelevant to the one-sided single layer medium; and read stability of1,000,000 times or more. Therefore, each of the storage mediums obtained“good” characteristics.

Example 3

In example 3, as in example 1, a one-sided single layer storage mediumwas produced. Ca was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 4

In example 4, as in example 1, a one-sided single layer storage mediumwas produced. Ce was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 5

In example 5, as in example 1, a one-sided single layer storage mediumwas produced. Co was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 6

In example 6, a one-sided single layer and a one-sided double layerstorage mediums were produced. Ga was used as an additive element of anAg-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at% were used as amounts of additives; and three types (1), (2), and (3)were used as organic dye materials for recording films. As in example 1,12 types of storage mediums were produced, and evaluation of recordingand reproducing characteristics were carried out. With respect to amedium whose Ga additive amounts are 0.05 at % and 1 at %, a one-sideddouble layer storage medium was produced, and with respect to a mediumwhose Ga additive amounts were 2 at % and 5 at %, a one-sided singlelayer storage medium was produced, respectively, and evaluation wascarried out. Each of the storage mediums achieved the target values;SbER of 5.0×10⁻⁵ or less; PRSNR of 15.0 or more; modulation of 0.4 ormore; reflectivity of 4% or more relevant to the one-sided double layermedium in both of L0 and L1 and 14% or more relevant to the one-sidedsingle layer medium; and read stability of 1,000,000 times or more.Therefore, each of the storage mediums obtained “good” characteristics.

Example 7

In example 7, as in example 1, a one-sided single layer storage mediumwas produced. La was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 8

In example 8, one-sided single layer and double layer storage mediumswere produced. Mg is used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. With respect to a mediumwhose Mg additive amounts are 0.05 at % and 1 at %, a one-sided doublelayer storage medium was produced, and with respect to a medium whose Mgadditive amounts were 2 at % and 5 at %, a one-sided single layerstorage medium was produced, respectively, and evaluation was carriedout. Each of the storage mediums achieved the target values; SbER of5.0×10⁻⁵ or less; PRSNR of 15.0 or more; modulation of 0.4 or more;reflectivity of 4% or more relevant to the one-sided double layer mediumin both of L0 and L1 and 14% or more relevant to the one-sided singlelayer medium; and read stability of 1,000,000 times or more. Therefore,each of the storage mediums obtained. “good” characteristics.

Example 9

In example 9, as in example 1, a one-sided single layer storage mediumwas produced. N was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 10

In example 10, as in example 1, a one-sided single layer storage mediumwas produced. Ni was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 11

In example 11, as in example 1, a one-sided single layer storage mediumwas produced. Nd was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 12

In example 12, as in example 1, a one-sided single layer storage mediumwas produced. Pd was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 13

In example 13, as in example 1, a one-sided single layer storage mediumwas produced. Y was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 14

In example 14, as in example 1, a one-sided single layer storage mediumwas produced. W was used as an additive element of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as amounts of additives; and three types (1), (2), and (3) wereused as organic dye materials for recording films. As in example 1, 12types of storage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 14% or more;and read stability of 1,000,000 times or more. Therefore, each of thestorage mediums obtained “good” characteristics.

Example 15

In example 15, a one-sided single layer and a one-sided double layerstorage mediums were produced. Zr is used as an additive element of anAg-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at% were used as amounts of additives; and three types (1), (2), and (3)were used as organic dye materials for recording films. As in example 1,12 types of storage mediums were produced, and evaluation of recordingand reproducing characteristics were carried out. With respect to amedium whose Zr additive amounts are 0.05 at % and 1 at %, a one-sideddouble layer storage medium was produced, and with respect to a mediumwhose Zr additive amounts were 2 at % and 5 at %, a one-sided singlelayer storage medium was produced, respectively, and evaluation wascarried out. Each of the storage mediums achieved the target values;SbER of 5.0×10⁻⁵ or less; PRSNR of 15.0 or more; modulation of 0.4 ormore; reflectivity of 4% or more relevant to the one-sided double layermedium in both of L0 and L1 and 14% or more relevant to the one-sidedsingle layer medium; and read stability of 1,000,000 times or more.Therefore, each of the storage mediums obtained “good” characteristics.

Example 16

In example 16, as in example 1, a one-sided single layer storage mediumwas produced, Al and Mg were used as additive elements of an Ag-alloyreflection film, four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused as total additive amounts of Al and Mg; and three types (1), (2),and (3) were used as organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Example 17

In example 17, a one-sided single layer and a one-sided double layerstorage mediums were produced. Au and Bi were used as additive elementsof an Ag-alloy reflection film, four types 0.05 at %, 1 at %, 2 at %,and 5 at % were used as total additive amounts of Au and Bi; and threetypes (1), (2), and (3) were used as organic dye materials for recordingfilms. As in example 1, 12 types of storage mediums were produced, andevaluation of recording and reproducing characteristics were carriedout. With respect to a medium whose Ga additive amounts are 0.05 at %and 1 at %, a one-sided double layer storage medium was produced, andwith respect to a medium whose Ga additive amounts were 2 at % and 5 at%, a one-sided single layer storage medium was produced, respectively,and evaluation was carried out. Each of the storage mediums achieved thetarget values; SbER of 5.0×10⁻⁵ or less; PRSNR of 15.0 or more;modulation of 0.4 or more; reflectivity of 4% or more relevant to theone-sided double layer medium in both of L0 and L1 and 14% or morerelevant to the one-sided single layer medium; and read stability of1,000,000 times or more. Therefore, each of the storage mediums obtained“good” characteristics.

Example 18

In example 18, a one-sided single layer and a one-sided double layerstorage mediums were produced. Bi and Ga were used for additive elementsof an Ag-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %,and 5 at % were used for total additive amounts of Bi and Ga; and threetypes (1), (2), and (3) were used for organic dye materials forrecording films. As in example 1, 12 types of storage mediums wereproduced, and evaluation of recording and reproducing characteristicswere carried out. With respect to a medium whose Ga additive amounts are0.05 at % and 1 at %, a one-sided double layer storage medium wasproduced, and with respect to a medium whose Ga additive amounts were 2at % and 5 at %, a one-sided single layer storage medium was produced,respectively, and evaluation was carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 4% or morerelevant to the one-sided double layer medium in both of L0 and L1 and14% or more relevant to the one-sided single layer medium; and readstability of 1,000,000 times or more. Therefore, each of the storagemediums obtained “good”-characteristics.

Example 19

In example 19, as in example 1, a one-sided single layer storage mediumwas produced. Au and Ce were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Au and Ce; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or (more; reflectivity of 14%or more; and read stability of 1,000,000 times or more. Therefore, eachof the storage mediums obtained “good” characteristics.

Example 20

In example 20, as in example 1, a one-sided single layer storage mediumwas produced. Au and Co were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Au and Co; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Example 21

In example 21, as in example 1, a one-sided single layer storage mediumwas produced. Au and Ni were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Au and Ni; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Example 22

In example 22, as in example 1, a one-sided single layer storage mediumwas produced. Au and Mg were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Au and Mg; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Example 23

In example 23, a one-sided single layer and a one-sided double layerstorage mediums were produced. Bi and Mg were used for additive elementsof an Ag-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %,and 5 at % were used for total additive amounts of Bi and Mg; and threetypes (1), (2), and (3) were used for organic dye materials forrecording films. As in example 1, 12 types of storage mediums wereproduced, and evaluation of recording and reproducing characteristicswere carried out. With respect to a medium whose Ga additive amounts are0.05 at % and 1 at %, a one-sided double layer storage medium wasproduced, and with respect to a medium whose Ga additive amounts were 2at % and 5 at %, a one-sided single layer storage medium was produced,respectively, and evaluation was carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 4% or morerelevant to the one-sided double layer medium in both of L0 and L1 and14% or more relevant to the one-sided single layer medium; and readstability of 1,000,000 times or more. Therefore, each of the storagemediums obtained “good” characteristics.

Example 24

In example 24, a one-sided single layer and a one-sided double layerstorage mediums were produced. Bi and N were used for additive elementsof an Ag-alloy reflection film; four types 0.05 at %, 1 at %, 2 at %,and 5 at % were used for total additive amounts of Bi and N; and threetypes (1), (2), and (3) were used for organic dye materials forrecording films. As in example 1, 12 types of storage mediums wereproduced, and evaluation of recording and reproducing characteristicswere carried out. With respect to a medium whose Ga additive amounts are0.05 at % and 1 at %, a one-sided double layer storage medium wasproduced, and with respect to a medium whose Ga additive amounts were 2at % and 5 at %, a one-sided single layer storage medium was produced,respectively, and evaluation was carried out. Each of the storagemediums achieved the target values; SbER of 5.0×10⁻⁵ or less; PRSNR of15.0 or more; modulation of 0.4 or more; reflectivity of 4% or morerelevant to the one-sided double layer medium in both of L0 and L1 and14% or more relevant to the one-sided single layer medium; and readstability of 1,000,000 times or more. Therefore, each of the storagemediums obtained “good” characteristics.

Example 25

In example 25, as in example 1, a one-sided single layer storage mediumwas produced. Bi and Pd were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Bi and Pd; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Example 26

In example 26, as in example 1, a one-sided single layer storage mediumwas produced. Bi and Zr were used as additive elements of an Ag-alloyreflection film; four types 0.05 at %, 1 at %, 2 at %, and 5 at % wereused for total additive amounts of Bi and Zr; and three types (1), (2),and (3) were used for organic dye materials for recording films. As inexample 1, 12 types of storage mediums were produced, (and evaluation ofrecording and reproducing characteristics were carried out. Each of thestorage mediums achieved the target values; SbER of 5.0×10⁻⁵ or less;PRSNR of 15.0 or more; modulation of 0.4 or more; reflectivity of 14% ormore; and read stability of 1,000,000 times or more. Therefore, each ofthe storage mediums obtained “good” characteristics.

Comparative Example 1

In comparative example 1, as in example 1, a one-sided single layerstorage medium was produced. Al was used as an additive element of anAg-alloy reflection film; two types of 0.04 at % and 6 at % were used asadditive amounts; and a phthalocyanine based organic dye and super-greendye (IRGAPHOR Ultragreen MX available from Ciba Speciality Chemicals)were used as organic dye materials for recording films. Three types ofstorage mediums were produced, and evaluation of recording andreproducing characteristics were carried out. In the case where theadditive amount of Al contained in the Ag alloy was defined as 6 at %,the modulation and reflectivity did not meet 0.4 or more and 14% or morewhich are their target values, and was “unacceptable”. In addition, inthe case where the additive amount of Al contained in the Ag alloy wasdefined as 0.04 at %, in particular, read stability did not achieve1,000,000 times or more. Therefore, each of the storage mediums achievedonly “unacceptable” characteristics.

Comparative Example 2

In comparative example 2, as in example 1, a one-sided single layerstorage medium was produced. Cu was used as an additive element of anAg-alloy reflection film; two types of 0.04 at % and 6 at % were used asadditive amounts; and a phthalocyanine based organic dye and super-greendye (IRGAPHOR Ultragreen MX available from Ciba Speciality Chemicals)were used as organic dye materials for recording films. A storage mediumwas produced, and evaluation of recording and reproducingcharacteristics were carried out. In the case where the additive amountof Cu contained in the Ag alloy was defined as 6 at %, the modulationand reflectivity did not meet 0.4 or more and 14% or more which aretheir target values, and was “unacceptable”. In addition, in the casewhere the additive amount of Cu contained in the Ag alloy was defined as0.04 at %, in particular, read stability did not achieve 1,000,000 timesor more. Therefore, each of the storage mediums achieved only“unacceptable” characteristics.

Comparative Example 3

In comparative example 3, as in example 1, a one-sided single layerstorage medium was produced. Pd was used as an additive element of anAg-alloy reflection film; two types of 0.04 at % and 6 at % were used asadditive amounts; and a phthalocyanine based organic dye and super-greendye (IRGAPHOR Ultragreen MX available from Ciba Speciality Chemicals)were used as organic dye materials for recording films. A storage mediumwas produced, and evaluation of recording and reproducingcharacteristics were carried out. In the case where the additive amountof Pd contained in the Ag alloy was defined as 6 at %, the modulationand reflectivity did not meet 0.4 or more and 14% or more which aretheir target values, and was “unacceptable”. In addition, in the casewhere the additive amount of Pd contained in the Ag alloy was defined as0.04 at %, in particular, read stability did not achieve 1,000,000 timesor more. Therefore, each of the storage mediums achieved only“unacceptable” characteristics.

According to an embodiment, a storage medium comprises a transparentresin substrate on which a groove is formed; a recording layer formed onthe groove on the transparent resin substrate, the recording layer usingan organic dye material and recording information with a light beam of620 nm or less in wavelength; a reflection layer formed on the recordinglayer; and a prevention layer formed between the recording layer and thereflection layer, the prevention layer preventing degradation ofcharacteristics of the reflection layer.

In the storage medium, the reflection layer may comprise Ag and anadditive element selected from Al, Au, Bi, Ca, Ce, Co, Cu, Ga, La, Mg,N, Ni, Nd, Pd, Pt, Rh, Y, W, and Zr.

In the storage medium, a total amount of the additive elements may rangefrom 0.05 at % to 5 at %.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the inventions. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the inventions. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the inventions.

1. A storage medium comprising: a recording layer formed of an organicdye material; a reflection layer formed of a silver alloy, light whichis passed through the recording layer being reflected by the reflectionlayer; and a prevention layer provided between the reflection layer andthe recording layer which prevents a characteristic change of thereflection layer, wherein, the recording layer includes an unrecordedarea, information is recordable by light having a wavelength of 405 nm,an intensity of light reflected by the reflection layer and through arecording area of the recording layer is higher than an intensity oflight reflected by the reflection layer and through the unrecorded area,and a light absorbance in the unrecorded area at a wavelength of 355 nmbeing not smaller than 40% of the light absorbance in the unrecordedarea at a peak absorption wavelength in a range of wavelengths longerthan 405 nm, the peak absorption wavelength being a wavelength for whichthe light absorbance in the unrecorded area in the range of wavelengthslonger than 405 nm is highest.
 2. The storage medium according to claim1, wherein the prevention layer prevents a recording and reproductioncharacteristic change due to reaction between the reflection layer andthe recording layer.
 3. The storage medium according to claim 1, whereinthe reflection layer comprises silver Ag and an additive elementselected from: aluminum Al; gold Au; bismuth Bi; calcium Ca; cerium Ce,cobalt Co, gallium Ga, lanthanum La; magnesium Mg; nitrogen N; nickelNi; neodium Nd; palladium Pd; yttrium Y; tungsten W; and zirconium Zr.4. The storage medium according to claim 3, wherein the additive elementranges from 0.05 at % to 5 at % in a total atom number of the additiveelement relative to Ag content.
 5. A method for reproducing informationrecorded in a storage medium storing modulated data, the mediumcomprising: a recording layer formed of an organic dye material; areflection layer formed of a silver alloy, light which is passed throughthe recording layer being reflected by the reflection layer; and aprevention layer provided between the reflection layer and the recordinglayer, wherein, the recording layer includes an unrecorded area,information is recordable by light having a wavelength of 405 nm, anintensity of light reflected by the reflection layer and through arecording area of the recording layer is higher than an intensity oflight reflected by the reflection layer and through the unrecorded area,and a light absorbance in the unrecorded area at a wavelength of 355 nmbeing not smaller than 40% of the light absorbance in the unrecordedarea at a peak absorption wavelength in a range of wavelengths longerthan 405 nm, the peak absorption wavelength being a wavelength for whichthe light absorbance in the unrecorded area in the range of wavelengthslonger than 405 nm is highest, the method comprising: irradiating thestorage medium with a light beam of 405 nm in wavelength; andreproducing information recorded in the storage medium based on areflection light beam of the irradiated light beam.
 6. A method forrecording information in a storage medium storing modulated data, themedium comprising: a recording layer formed of an organic dye material;a reflection layer formed of a silver alloy, light which is passedthrough the recording layer being reflected by the reflection layer; anda prevention layer provided between the reflection layer and therecording layer, wherein, the recording layer includes an unrecordedarea, information is recordable by light having a wavelength of 405 nm,and an intensity of light reflected by the reflection layer and througha recording area of the recording layer is higher than an intensity oflight reflected by the reflection layer and through the unrecorded area,and a light absorbance in the unrecorded area at a wavelength of 355 nmbeing not smaller than 40% of the light absorbance in the unrecordedarea at a peak absorption wavelength in a range of wavelengths longerthan 405 nm, the peak absorption wavelength being a wavelength for whichthe light absorbance in the unrecorded area in the range of wavelengthslonger than 405 nm is highest, the method comprising: recording data onthe storage medium.